Forecasts

Warm temps Wednesday, another chance for thunderstorms in Thornton

We have certainly been loving the thunderstorms of the last couple afternoons. Today, we stand another chance for some activity plus slightly cooler temperatures.

Mostly sunny skies start us off and will be with us this morning. Then, as in recent days, cloud cover will increase in the afternoon. High temperatures will top out in the mid to upper 80s. The afternoon brings another chance for thunderstorms during a somewhat brief window. Look for the best chances from about 2:00pm to 4:00pm.

This evening, some thunderstorms may linger but activity, if any, will be greatly decreased. Skies tonight will see clearing and overnight lows will dip to around 60 degrees.

Weather History

July 14 to July 20: This Week in Denver Weather History

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This Week in Denver Weather History

Monsoonal rain, dangerous lightning and large hail are all par for the course as we see in our look back at this week in Denver weather history. But, what about snow? Yes, you read that right. Denver did actually record snowfall on July 17, 1872 but because it occurred before official snowfall measurements began in the young Mile High City, it doesn’t count. See below for complete details.

From the National Weather Service:

1-18

In 1874…a streak of 18 consecutive days of 90 degrees tied for second with another streak that was later set in the summer of 1901. The record of 24 consecutive days was established in the summer of 2008.
1-31

In 2012…it was the hottest July on record in Denver since weather records began in 1872. The average temperature for the month was 78.9 degrees which was 4.7 degrees above normal. There were 27 days in which the high temperature equaled or exceeded 90 degrees…which established a new record. There were also 7 days in which the temperature equaled or exceeded 100 degrees which tied the record set in 2005.

6-23

In 1901…a streak of 18 consecutive days of 90 degrees tied for second with another streak set in the summer of 1874. The record of 24 consecutive days was established in the summer of 2008.

7-25

In 1934…a streak of 15 consecutive days of 90 degrees ranked 5th on the list of hot streaks. The record of 24 consecutive days was established in the summer of 2008.

13-5

In 2008…a streak of 24 consecutive days of 90 degrees shattered the previous record of 18 consecutive days established in 1901 and 1874. Ironically…no new single day record high temperatures were set in the month of July. In August however…a record of 104 degrees was set on the 1st…and another record of 103 degrees was set on the 2nd. In addition…a record low min of 70 degrees was set on August 2nd.

14

In 1878…the temperature reached a high of 100 degrees in downtown Denver.

In 1906…a thunderstorm produced north winds sustained to 52 mph and 0.53 inch of rain in 10 minutes.

In 1912…a heavy thunderstorm cloudburst in the late afternoon combined with a similar storm to the south of the city to produce widespread flooding on Cherry Creek in downtown Denver…which resulted in two deaths and several injuries. The flooding was the worst since 1864 and covered around 3 square miles of lower downtown. Bridges along Cherry Creek were washed out and water lapped at the floor of the Broadway bridge over the South Platte River…causing authorities to declare it unsafe except for pedestrians. By nightfall… Union Depot was under 2 to 3 feet of water…and railroad and street car traffic was stalled. Those forced from their homes by the surging flood waters took refuge in the Denver auditorium. The flood waters caused great damage to the sewerage system…parkways…bridges and residences and commercial warehouses near Cherry Creek in the wholesale district. Flood damage was estimated at several million dollars. Heavy thunderstorm rainfall of 2.00 inches…of which nearly 1.75 inch fell in 30 minutes in central Denver… Was accompanied by severe thunderstorm winds sustained to 55 mph with gusts as high as 74 mph.

In 1933…thunderstorm rainfall was only 0.01 inch…but northwest winds sustained to 37 mph with gusts to 47 mph produced a dust storm for about 10 minutes during the late afternoon.

In 1967…heavy rain flooded areas of north and west metro Denver…and high water closed street intersections in the city. Crops were damaged…and 200 chickens drowned by flooding northwest of Denver where farm buildings and irrigation facilities were also damaged.

In 1969…a thunderstorm wind gust to 51 mph was recorded at Stapleton International Airport.

In 1975…heavy rains caused locally heavy flash flooding along Niver Creek south of Thornton and in other parts of north metro Denver. Over 40 thousand dollars in damage to public property was reported…and numerous homes and yards were damaged.

In 1986…thunderstorm winds blew down a power line in west- central Jefferson County. The storm…as it moved into Denver…snapped tree limbs and damaged a fence near Washington Park. Wind gusts in the area were estimated at 80 to 85 mph.

In 1990…thunderstorm wind gusts to 58 mph were recorded at Buckley Field in Aurora. No damage was reported. Winds gusted to 44 mph at Stapleton International Airport.

In 1993…a severe thunderstorm moved across southern sections of metro Denver. Dime size hail fell in Lakewood…and hail up to one inch diameter was measured at Cherry Creek Reservoir. Later in the afternoon…hail to one inch diameter fell in Golden and Arvada.

In 1994…hail to 1 1/4 inches in diameter fell north of Bennett.

In 1998…dry microburst winds estimated to 70 mph snapped tree branches up to 4 inches in diameter in Brighton where some road signs were twisted and blown down. At Denver International Airport…dry microburst winds gusted to 61 mph.

In 1995…thunderstorm winds gusted to 62 mph near Strasburg.

In 2001…a severe thunderstorm dumped hail to 3/4 inch in diameter in the foothills about 10 miles northwest of Golden.

In 2011…severe thunderstorms in the Denver metropolitan area produced very heavy rain…large hail and damaging winds. The strong winds toppled a few trees and the heavy rain caused street flooding and minor flash flooding. Several cars were stranded at the intersection of Santa Fe Drive and Oxford…and near Broadway and U.S. Highway 285. A 16-yr old teenager was seriously injured when he tried to retrieve a ball along the banks of west toll gate creek. He was pulled from the swollen creek and died several days later. Hail up to one inch in diameter was reported around the area. The thunderstorms also produced frequent lightning. One strike sparked a fire at aspen academy…a private school in greenwood village. Most of the damage was confined to the roof and attic. In Englewood…a 40-ft tree was blown into a house and knocked down some power lines. At Denver International Airport…a severe thunderstorm produced sustained winds of 47 mph and a peak wind gust to 68 mph.

In 2019…a Denver man was killed and his wife injured after he was struck by lightning when they were hiking near the Bear Peak West Ridge Trail. The man was likely hit from a direct lightning strike to his upper body. His wife was not directly hit…but injured by the electrical current from the strike that hit her husband.

14-15

In 1985…thunderstorms dumped heavy rain and hail at numerous locations along the Front Range from Denver north. Some of the heaviest rain fell in northern and western suburbs of Denver. Up to 2.6 inches of rain drenched Arvada…and Thornton was soaked with 2 inches in 45 minutes. At least 5 homes in Arvada suffered extensive damage from water and mud…and many streets and basements were flooded.

In southern Jefferson County…11 homes were struck by lightning.

15

In 1879…a terrific hail storm occurred in the vicinity of Buffalo Station on the South Park Railroad in the South Platte River Canyon about 39 miles south of Denver. Stones as large as hen’s eggs fell thick and fast and broke nearly every pane of glass in the windows of the building. A “waterspout” or cloudburst caused much loss of property from flash flooding on a nearby gulch. The torrent of water caused a deafening roar as it uprooted trees and carried huge Boulders and other debris. It struck the house and sawmill simultaneously and carried them away like straws…leaving little behind. The water continued to rush down the gulch for several hours. Serious damage was done to the south park railroad. The track and roadbed were destroyed for several miles. At about the same time…heavy rains in the vicinity of the headwaters of Cherry Creek produced a rapid rise in the creek…which drowned a few head of cattle and washed away two footbridges and some fences. Only 0.10 inch of rainfall was recorded in Denver.

In 1896…a thunderstorm produced sustained southwest winds to 40 mph with gusts to 46 mph.

In 1902…the temperature reached a high of 100 degrees in downtown Denver…which was a record maximum for the date.

In 1929…a thunderstorm did considerable damage to property in the eastern portion of the city. Heavy hail ranging in size from 1/4 to 3/4 inch in diameter…severe lightning… And high winds accompanied the heavy rain. Basements were flooded…and streets were impassable in places for several hours due to the heavy rainfall. Lightning damaged several telephone poles. Hail did extensive damage to gardens and flowers. The hail was up to a foot deep in places. There was no estimate of damage from the storm. A thunderstorm produced only a trace of rain and east winds to 24 mph in downtown Denver.

In 1959…thunderstorm rain totaled 0.41 inch in 8 minutes and winds gusted to an estimated 50 mph near downtown Aurora where half inch diameter hail was also reported. After the storm moved to the east…complete double rainbows were observed from the weather bureau office at Stapleton Airport.

In 1962…hail pelted the area in Adams County around Henderson and Brighton…causing extensive damage to corn…grain… Beets…and row crops. Crop damage was estimated at 250 thousand dollars.

In 1963…a man received severe burns when struck by lightning while painting a building in south Denver.

In 1965…a state patrolman sighted a tornado near Bennett. It touched down over open ground…but caused no damage.

In 1967…heavy rains flooded streets and underpasses in south Denver. Heavy rain and minor wind damage were reported in Wheat Ridge…Aurora…Englewood…and Littleton. Basements were flooded and power disrupted. The clouds and rain resulted in a high temperature of only 72 degrees…which was a record low maximum for the date.

In 1974…a severe lightning storm damaged several homes and caused a number of power outages in both Denver and western Arapahoe counties.

In 1975…lightning killed a girl west of Boulder.

In 1982…winds gusted to 60 mph at Stapleton International Airport…and strong winds blew down walls at a construction site in Aurora where a nearby tree was uprooted.

In 1985…0.79 inch of rain fell in 30 minutes at Castle Rock. Much of the town lost power when lightning struck the town’s transformer.

In 1992…a man was struck by lightning while horseback riding near Castle Rock. Two people were struck by lightning near Highlands Ranch in south metro Denver. A man was struck by lightning while riding in the back of a pick-up truck in Franktown. All received minor injuries. Strong thunderstorms moved through east metro Denver…producing large hail and flash flooding. Hail up to 1 1/4 inches in diameter fell near Buckley Air National Guard base. Rainfall of 1 to 3 inches fell in Aurora in less than an hour…leaving water up to 18 inches deep in some areas. Thunderstorm rainfall was measured at 0.97 inch at Stapleton International Airport…where 3/8th inch diameter hail fell and south winds gusted to 44 mph.

In 1993…dime size hail fell in Golden. National weather service observers at Stapleton International Airport sighted a small rope-like funnel overhead for about 3 minutes before it dissipated.

In 1994…a small…short-lived tornado caused damage to a house under construction in Parker.

In 1995…thunderstorm winds of unknown strength downed trees and branches…damaging a porch and nearby cars in Denver.

In 1998…hail to 7/8 inch in diameter fell near Keenesburg.

In 2000…this date marked the end of a near record hot streak for metro Denver. The high temperature at Denver International Airport equaled or exceeded the 90-degree mark for 17 consecutive days…from June 29th. This was one day short of equaling the all-time record. The record of 18 consecutive days was set in two different years…July 1st-18th…1874 and July 6th-23rd…1901.

In 2005…severe thunderstorms produced large hail over southeast metro Denver. Hail as large as 1.75 inches in diameter fell in southwest Aurora along with 7/8 inch hail in Centennial. Hail to 3/4 inch in diameter was measured near Centennial Airport and near Watkins.

In 2015…A severe thunderstorm produced a peak wind gust to 60 mph from the northwest at Denver International Airport. In addition…0.06 inches of rainfall was also observed.

In 2016…large hail ranging in size from 1 to 2 inches in diameter struck Aurora…Castle Rock…Centennial…Greenwood Village and southeast Denver. The hail shattered windshields and caused extensive damage to vehicles.

15-16 Continue reading July 14 to July 20: This Week in Denver Weather History →

Weather History

July 7 to July 13: This Week in Denver Weather History

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This Week in Denver Weather History

Severe weather becomes a bit less common as we get further into summer but the threat is never gone as we see in our look back at this week in Denver weather history. Many notable events related to severe thunderstorms have occurred including flooding rain, tornadoes and damaging hail.

From the National Weather Service:

29-15

In 2000…the 29th marked the beginning of a near record hot streak for metro Denver. The high temperatures…as recorded at Denver International Airport…exceeded the 90 degree mark for 17 consecutive days from June 29th through July 15th. The record of 24 consecutive 90 degree or above days was set from July 13th through August 5th…2008.

1-18

In 1874…a streak of 18 consecutive days of 90 degrees tied for second with another streak that was later set in the summer of 1901. The record of 24 consecutive days was established in the summer of 2008.

4-8

In 1989…one of the most intense heat waves on record roasted metro Denver. The temperature reached 100 degrees or more on 5 consecutive days. The city had previously never recorded more than 2 straight 100-degree days since records began in 1872. Water and electricity usage reached all-time highs. The heat wave created extremely dry weather conditions…which contributed to a major forest fire in Boulder canyon on July 9th. The temperature reached 103 degrees on the 8th…and the mercury climbed to 101 degrees on both the 4th and 5th…and to 102 degrees on both the 6th and 7th. The low temperature of 68 degrees on the 8th equaled the record high minimum for the date.

6-23

In 1901…a streak of 18 consecutive days of 90 degrees tied for second with another streak set in the summer of 1874. The record of 24 consecutive days was established in the summer of 2008.

7

In 1905…a thunderstorm produced sustained northeast winds to 40 mph…but only a trace of rain.

In 1933…heavy cloudbursts during the afternoon in the Idledale area and on Saw Mill Gulch caused flash flooding on bear creek resulting in 7 deaths. Flooding in Morrison was compounded when a wall of water as high as 15 feet swept down Mount Vernon Creek. The flooding caused extensive damage to the Bear Creek Canyon highway.

In 1959…wind gusts to 45 mph at Stapleton Airport…but higher in other areas…damaged power lines and buildings and caused widespread minor damage from falling trees and broken limbs. A field house under construction at Adams County high school in Commerce City sustained severe damage.

In 1963…farm buildings east of Boulder were possibly damaged by a small tornado as there were unconfirmed reports of a funnel cloud in the area.

In 1967…a storm of cloudburst proportion caused damage from flooding in southwest and south Denver. Unofficial reports indicated rainfall of 2.00 inches in 30 minutes and more than 3.00 inches total from the storm. Streets and buildings were flooded by the heavy run-off. Hail in some areas contributed to flooding by blocking storm drains. Water accumulated 12 to 14 feet deep in several underpasses and some street intersections. A young woman drowned when she tried to cross a flooded street and was swept off her feet and trapped under a parked car. Water reached a depth of 5 feet in the street. Police rescued numerous stranded motorists. The roof and wall of a flat roofed store building collapsed under the weight of deep water on the roof. Cars were washed over curbs in many areas. In southwest metro Denver…100 to 150 homes were flooded. Hail caused damage in other areas of Denver and in Aurora. Wind toppled trees in several areas. Snowplows were called out to clear hail from some highways and runways at Stapleton International Airport. Lightning damaged trees and power lines and started a fire…which extensively damaged an automobile dealership. Thunderstorm rainfall totaled 0.83 inch at Stapleton International Airport.

In 1981…severe thunderstorms produced 3/4 inch hail over east Denver. About 1 1/2 inches of rain fell in Littleton. Thunderstorm winds gusted to 45 mph at Stapleton International Airport.

In 1983…tennis ball size hail fell about 5 miles north of Boulder; it was soft and caused no damage.

In 1987…a weak tornado touched down in Castle Rock. Several weak tornadoes were observed in the area. No damage was reported.

In 1988…lightning struck a sign at a bank near Louisville… Damaging it and causing a smoldering fire that resulted in smoke damage to the bank and an adjacent building. Heavy thunderstorm rain…accompanied by 1/2 inch diameter hail at Stapleton International Airport…briefly reduced the visibility to 1/4 mile. Rainfall totaled 1.41 inches… But 1.12 inches fell in 32 minutes.

In 2001…severe thunderstorms dumped large hail across north metro Denver. Hail to 1 3/4 inches in diameter fell near Erie with 7/8 inch hail measured in Thornton.

In 2004…a 9-year-old boy was struck by lightning while at a playground in Arvada. The umpire at a nearby baseball game…along with 2 passers-by…administrated CPR and resuscitated the boy who had quit breathing. The boy suffered first and second degree burns…but was released from the hospital in less than 24 hours. A dry microburst over Denver International Airport produced a peak wind gust to 61 mph.

In 2006…up to 3 inches of heavy thunderstorm rainfall in the Hayman wildfire burn area produced destructive flash flooding along west creek between the towns of Deckers and Westcreek in southwest Douglas County. Horse Creek…which drains into West Creek…swelled from a normally small creek into a raging torrent…25 to 30 feet deep and 300 feet wide. The wall of water damaged or destroyed about 30 sections of a 5 mile stretch of State Highway 67…which parallels West Creek. Several homes were extensively damaged or destroyed. No injuries were reported…but several people had to be rescued…due to extensive damage to access roads and bridges in the area. Reconstruction was estimated at 13.3 million dollars.

In 2011…heavy rain associated with a wet microbursts produced over 3 inches of rain in 90 minutes across southeast Denver. In Denver…some underpasses were flooded with several feet of water which stranded motorists. As a result…the fire department conducted at least 10 water rescues. Some basements were inundated with up to 4 feet of water which caused extensive flood damage. The Platte Valley and Western Model Railroad Club’s model train display in Union Station was also damaged when 3 to 4 inches of mud and water spilled over some of the command and control systems. Several display modules and scenery pieces in a storage room were also damaged. The entire display spanned more than one thousand feet of track in a room that was once used as the jail at union station in the 1900s. Urban and small stream flooding was reported across the surrounding Denver suburbs. The storm left about 28000 Xcel customers without power when the storm snapped trees and power lines. In addition…heavy rain produced flash flooding in the Four Mile Canyon burn scar. Four debris slides occurred along Four Mile Canyon Drive…including one that was 100 yards wide and 4 feet deep. Several rockslides were reported in Lefthand and Boulder canyons. At Denver International Airport…1.04 inches of rain was observed. A peak wind gust of 46 mph from the southeast was also observed.

In 2014…an Arvada resident was injured by a nearby lightning strike while he recorded a video of a thunderstorm with his cell phone. He was standing in his garage…when a nearby lightning bolt knocked him out. He suffered overall body aches and had a ringing sensation in one of his ears. In Denver… lightning caused a power outage that affected the RTD light rail lines for a short time. In Castle Pines…lightning sparked a small attic fire. Severe thunderstorms produced large hail…from quarter to golfball size…and damaging winds across Arapahoe…Boulder and Jefferson Counties including: northwest Arvada…Littleton and Louisville. Flash flooding was reported near Evergreen in central Jefferson County. Heavy rain…up to 2 inches in one hour…flooded several residences and washed out several bridges along Forest Estate Road. Heavy rainfall also produced street flooding in Denver along with some basement flooding. The strong winds…estimated to 60 mph… downed trees and power lines in southwest Littleton. At Denver International Airport…0.15 inches of rainfall was observed along with a peak wind gust to 42 mph from the southeast.

In 2020…a thunderstorm produced a peak wind gust to 63 mph near Bennett.

7-25

In 1934…a streak of 15 consecutive days of 90 degrees ranked 5th on the list of hot streaks. The record of 24 consecutive days was established in the summer of 2008.

8

In 1905…a thunderstorm produced 0.82 inch of rainfall and northeast winds sustained to 48 mph.

In 1977…strong winds turned over 2 light aircraft at Arapahoe County airport…now Centennial Airport.

In 1987…a weak tornado was observed near Bennett.

In 1988…three separate tornadoes were sighted near Bennett. No damage was reported. One inch diameter hail was also reported.

In 1991…lightning started three house fires in Castle Rock. Damage totaled 13 thousand dollars. No injuries were reported.

In 1993…a dry thunderstorm microburst wind gust to 55 mph briefly reduced the surface visibility to 3 miles at Stapleton International Airport.

In 1997…one construction worker was killed and two others injured when a strong thunderstorm wind gust caused the scaffolding they were standing on to collapse near Parker. A dry microburst produced a wind gust to 54 mph at Denver International Airport.

In 1998…heavy thunderstorm rain forced the closure of Hampden Avenue between I-25 and Havana Street in southeast Denver. The high water made 2 or 3 lanes of the street impassable.

In 2001…severe thunderstorms produced large hail…damaging winds…and heavy rain across south metro Denver. Two people received minor injuries when a severe thunderstorm wind gust to 58 mph blew over several tents at the Cherry Creek arts festival. The same storm caused the roof of a hardware store in Tamarac Square to collapse. One employee received minor injuries when she was struck in the head by falling debris. The combination of intense rain and wind downed trees and power lines. Electrical power outages affected 35 thousand homes and businesses. At least 50 trees in city parks across south Denver were damaged. Up to 4.50 inches of thunderstorm rain fell across portions of southeast metro Denver. The underpass at I-25 and Parker road was inundated with 5 feet of water. Several other streets and underpasses in Aurora were also closed due to high water. Heavy rain caused extensive damage to several exhibits at the Cherry Creek arts festival. Flash flooding occurred when heavy thunderstorm rainfall caused toll gate creek to jump its banks. Several underpasses across south Denver had to be closed due to high water. A man received minor injuries when lightning struck a nearby tree at the Wellshire Golf Course. Hail as large as 1 1/4 inches in diameter fell in Englewood with 1 inch hail in the city of Denver…and 3/4 inch hail in Littleton. Thunderstorm winds gusted to 63 mph at Denver International Airport and to 62 mph in Englewood.

In 2005…a tornado touched down briefly near Brighton…but caused no damage.

In 2011…severe thunderstorms produced hail…up to 1 inch in diameter…and wind gusts to 60 mph across parts of Adams…Broomfield and Denver counties. At Denver International Airport…a peak wind gust to 59 mph from the west.

In 2017…a strong thunderstorm produced hail up to 7/8 inch in diameter in southwest Denver.

In 2019…a severe thunderstorm produced hail up to 1 inch in diameter near Dacono.

9

In 1872…a very brisk wind between 2:00 pm and 3:00 pm spread a cloud of dust and sand into the city.

In 1874…northeast winds at sustained speeds up to 36 mph blew immense clouds of dust from the prairie through the streets of the city around mid-morning. The houses across the street from the weather station were not visible at the peak of the storm.

In 1875…heavy thunderstorm rains caused stream flooding… Which damaged nearly all railroads into the city. Rainfall in the city was only 0.14 inch.

In 1953…heavy thunderstorm rains caused an estimated 2 million dollars damage from flooded stores and basements across metro Denver. The flood waters reached a depth of 3 feet on streets in some sections of the city…damaging streets and automobiles. The heavy rainfall at Lowry Air Force Base totaled 3.90 inches. At Stapleton Airport where the heavy rain briefly reduced the surface visibility to 1/2 mile…only 1.05 inches of rain were measured. North winds gusting to 52 mph caused some damage in east Denver.

In 1982…two small tornadoes were spotted east of Rocky Flats… And a tornado touched down briefly 5 miles east of Brighton. No damage was reported.

In 1984…heavy rain fell over southern sections of metro Denver. Rainfall totaled 1.50 inches in just 15 minutes between Littleton and Sedalia.

In 1987…a thunderstorm microburst produced a wind gust of 58 mph at Erie north of Denver.

In 1988…hail to 3/4 inch in diameter piled up 2 to 4 inches deep in Idaho Springs. Some basements were flooded and several thousand gallons of fuel were contaminated when water flooded a gasoline storage tank. A tornado sighted near Manilla 5 miles west of Bennett remained on the ground for 9 minutes. No damage was reported.

In 1990…a severe thunderstorm produced a tornado and heavy rain over northeast metro Denver. As much as 4 inches of rain fell in just 20 minutes in Commerce City…causing the South Platte River to rise quickly and flood lowland areas. The raging flood waters caused extensive damage to a 30-foot stretch of railroad track embankment…destroyed a railroad trestle and a nearby garage…and washed away a vintage 1960’s show car near east 58th Avenue and York Street. The car was found a couple of miles downstream in a pool of deep mud and murky water. Rainfall totaled 1.34 inches at Stapleton International Airport where 1/2 inch diameter hail fell. The same thunderstorm produced a brief tornado in a vacant field near 64th Avenue and Tower Road just east of the Rocky Mountain Arsenal. No damage was reported from the twister. Lightning from the storm caused power outages to as many as 7 thousand homes and businesses.

In 1996…a tornado (F0) was reported 5 miles south of Hudson. No damage was reported. Twin weak tornadoes (F0) formed for a short time near the northeast runways at Denver International Airport. Less than 15 minutes later…a weak tornado (F0) touched down in the employee parking lot at DIA. Several car windows were blown out…and a few vehicles sustained minor body damage from flying debris. Several signs were also blown down. Later…twin weak tornadoes (f0) touched down again in open country between DIA and Watkins.

In 2004…severe thunderstorms produced hail to 3/4 inch in diameter near tiny town and wind gusts to 66 mph in Bennett. A thunderstorm wind gust to 56 mph was measured at Denver International Airport.

In 2005…a thunderstorm produced a wind gust to 54 mph at Denver International Airport.

In 2020…severe thunderstorms produced damaging winds and large hail over parts of Adams…Arapahoe…and Weld counties. The hail generally ranged from 1 to 1 3/4 inches. The largest reports included 2 inch hail in Watkins…with 2 1/2 inch hail…11 miles east of Arapahoe Park. Near Brighton and Henderson…thunderstorm wind gusts up to 60 mph caused minor tree damage. At Denver International Airport…a peak wind gust to 36 mph was observed from the northwest. In addition…0.03 inches of rainfall was reported.

9-10

In 1980…a series of severe thunderstorms hit metro Denver… Dumping heavy rain and producing a spectacular lightning display lasting for several hours. A number of homes were damaged by lightning. Winds gusted to 60 mph at Stapleton International Airport where about half an inch of rain fell in just 10 minutes along with 1/4 inch diameter hail. The evening thunderstorms continued into the early morning hours with total rainfall of 1.35 inches at Stapleton International Airport.

In 1998…thunderstorm rainfall totaled 2.04 inches at the site of the former Stapleton International Airport.

10

In 1878…a lunar rainbow was observed during a light mist and fog.

In 1895…the temperature warmed to a high of only 53 degrees… The all-time record lowest maximum temperature for the month of July.

In 1967…golf ball size hail damaged aircraft at Jefferson County Airport near Broomfield.

In 1983…two people were injured when struck by lightning just southwest of Morrison. A man was injured when he was swept downstream by a flash flood on a tributary of Clear Creek in the canyon 8 miles west of Golden. Heavy thunderstorm rains caused mudslides which closed several roads. Rainfall amounts included: 1.75 inches in 20 minutes in southeast Denver…1.26 inches in 35 minutes in Boulder…2.14 inches in 2 hours in Lakewood…1.70 inches in 45 minutes in Aurora…and 1.25 inches in 30 minutes atop Floyd Hill in the foothills west of Denver.

In 1992…storm spotters reported 3/4 inch diameter hail near the construction site of the new Denver airport just northeast of the city.

In 1995…microburst winds toppled a pine tree 60 feet high and 2 feet in diameter in Denver. The tree fell and injured a man nearby. Microburst winds to 59 mph broke the glass on a door at the national weather service forecast office at the site of the former Stapleton International Airport.

In 1998…thunderstorm rainfall totaled 2.35 inches at Denver International Airport.

In 2000…three children were injured…one critically…when lightning hit a nearby tree at panorama point atop flagstaff mountain just west of Boulder. Lightning hit the tree…entered the ground…then struck the children. Lightning sparked a grassfire that burned about 50 acres at the Rocky Flats Environmental Test Facility. Also… Lightning sparked at least 6 fires in the Hudson and Keenesburg areas as thunderstorms…accompanied with heavy rain…large hail…and tornadoes…moved through southern Weld County. Over 2 inches of very heavy rain caused flooding along an I-76 exit ramp near Keenesburg. The fire department rescued 15 stranded motorists as high water inundated sections of the exit ramp and adjacent highway. Basements were also flooded in Keenesburg. One home reportedly had 7 feet of standing water in the basement before the rain subsided. A weak tornado (F0) touched down briefly near Brighton…but caused no damage.

In 2001…a severe thunderstorm dumped 7/8 inch diameter hail in Wheat Ridge.

In 2002…severe thunderstorms pelted the southern suburbs of metro Denver with large hail. Hail as large as 3 inches in diameter fell 6 miles southeast of Parker. Other large hail reports included 2 inch diameter hail around Centennial Airport and 3/4 inch hail near Sedalia and Deckers. Hail as large as 3/4 inch was also reported in Broomfield. Runoff from heavy thunderstorm rainfall in the Hayman fire burn area flooded Lost Creek Ranch with up to 18 inches of water just off State Highway 126. Floodwaters damaged a very expensive rug in the lodge. A driveway to a residence was washed away. In Douglas County…runoff damaged forest access roads in the turkey creek drainage.

In 2011…a severe thunderstorm produced intense microburst winds in southeast Boulder County. A peak wind gust to 75 mph was recorded in superior with gust to 58 mph…2 miles south of Lafayette. At Denver International Airport…a peak wind gust of 31 mph was recorded.

Continue reading July 7 to July 13: This Week in Denver Weather History →

Climatology, Thornton Weather

Thornton’s July 2023 preview: Summer heat really kicks in, thunderstorms common

July

Change is of course the one constant in Denver’s weather but come July, things actually get pretty consistent.

The standard formula for a day in July is a sunny morning, clouds developing in the late morning and early afternoon. Come mid-afternoon, thunderstorms are rolling off of the foothills and into the metro area and the eastern plains. These storms do occasionally reach severe status containing hail, gusty winds and heavy downpours of rain.

Check out our July weather preview for a complete look at what is in store for the month ahead.

Weather History

June 30 to July 6: This Week in Denver Weather History

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This Week in Denver Weather History

Dangerous lightning, damaging hail and even tornadoes make the highlights of our look back at this week in Denver weather history.

From the National Weather Service:

29-2

In 1990…almost a year to date after the record breaking heat in early July 1989…the third longest heat wave in Denver history started. From June 29th through July 2nd the temperature reached 100 degrees or more on four consecutive days. The highest reading of 102 degrees occurred on the 29th…30th…and 1st. Combined with the 102 degree reading on June 27th this would have been the longest heat wave on record…but the temperature climbed to only 98 degrees on June 28th.

29-15

In 2000…the 29th marked the beginning of a near record hot streak for metro Denver. The high temperatures…as recorded at Denver International Airport…exceeded the 90 degree mark for 17 consecutive days from June 29th through July 15th. The record of 24 consecutive 90 degree or above days was set from July 13th through August 5th…2008.

30

In 1879…dense smoke from mountain forest fires covered the city and obscured the sun as it set behind the mountains.

In 1900…a thunderstorm produced northwest winds to 44 mph with gusts to 58 mph…but only a trace of rain.

In 1917…north winds were sustained to 47 mph with gusts to 52 mph.

In 1942…a strong thunderstorm produced hail and heavy rainfall in south Denver. Leaves were stripped from trees and heavy rain caused street flooding which halted traffic. Hail of unknown size reached a depth of 9 inches on the ground.

In 1965…funnel clouds were observed to the south of Stapleton International Airport and in Jefferson County…15 miles southwest of the airport. Later…a tornado touched down briefly 1 mile east of Littleton…causing only minor damage. Another tornado was observed 12 miles southwest of Stapleton International Airport in Jefferson County. Hail to 3/4 inch in diameter fell in the bear valley area…12 miles south- southwest of Stapleton International Airport. Yet another tornado was sighted 10 miles northwest of the airport. Cloudbursts accompanied by hail battered areas of Arapahoe and Adams counties east of Denver…damaging ripening grain fields. At Lafayette…3.50 inches of rain fell in 30 minutes…causing some flooding.

In 1982…numerous funnel clouds were observed over southwest metro Denver. Only one funnel touched down near the intersection of Jewell and Kipling. The tornado was on the ground for about 5 minutes and caused no damage except for uprooting some trees. In addition…thunderstorms produced heavy rain and hail in the foothills west of Denver. Over an inch of rain fell in a short time near Idaho Springs… Causing clear creek to overflow its banks and flood a few low lying areas of the town. A few people were evacuated… And water and mud entered several stores. The heavy rain also washed out several roads. Hail piled up to a depth of 3 to 4 inches near Idaho Springs. Hail to 3/4 inch was reported at many places across metro Denver including Stapleton International Airport. Lightning struck a chemistry building on the University of Colorado campus in Boulder and started a small fire. Thunderstorm wind gusts to 60 mph were reported near Brighton.

In 1984…heavy rain caused some street and basement flooding in Littleton. One location received 1.56 inches of rain in 75 minutes.

In 1987…a weak tornado near Watkins stayed on the ground for 5 minutes.

In 1990…a small twister touched down in an open field just north of the rocky mountain arsenal. No damage was reported.

In 1998…hail as large as 1 inch in diameter fell near Evergreen.

In 2005…a severe thunderstorm produced hail as large as 3/4 inch near roggen. The hail destroyed a wheat field.

In 2006…the temperature reached a high of 98 degrees at Denver International Airport. This marked the 19th day in June with a maximum temperature of 90 degrees or more setting a new all-time record for the month.

In 2011…very strong thunderstorm winds were also observed across portions of the urban corridor. A peak wind gust to 65 mph was recorded…2 miles northeast of Boulder with a gust to 63 mph at Front Range airport at Watkins and 7 miles southeast of Denver International Airport. The peak wind gust measured at Denver International Airport itself was 45 mph. A severe thunderstorm also produced one inch in diameter hail 2 miles south-southeast of Parker. In addition…a lightning strike destroyed a home in north Denver.

In 2012…it was the hottest June in Denver since weather records began back in 1872. The average temperature for the month was 75.0 degrees which was 7.6 degrees above normal. There were a total of seventeen 90 degree days in the month of June. The highlight of record setting month was a stretch of five consecutive 100 degree days from the 22nd to the 26th. This was only the third time in Denver weather history in which this happened. Two of the high temperatures during the stretch peaked at 105 degrees… which set the all time record for the month of June and tied the all-time maximum temperature for Denver.

In 2019…eight hikers were injured by a nearby lightning strike at the Devil Head Lookout…west of Perry Park in Douglas County. Five hikers were able to walk out unassisted…while two other required assistance. Most complained of having tingling sensations…while two suffered from minor burns. The eighth victim suffered critical injuries and had to be carried out by stretcher and taken to a nearby hospital.

In 2023…a total of 5.35 inches of rain fell through the month of June…establishing the all time record for Denver. The previous record was 4.96 inches set 141 years earlier in 1882.

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In 1873…heavy rainfall overnight totaled 1.42 inches. Mountain peaks to the southwest of the city were covered with fresh snow on the morning of the 1st.

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In 1915…northeast winds sustained to 41 mph with gusts to 50 mph occurred just before a thundershower in the evening. Rainfall was only 0.07 inch.

In 1941…unusually heavy thunderstorm rains flooded basements and blocked traffic. Water was curb high on many downtown streets. The thunderstorm also pelted the city with hail of unknown size. Rainfall in downtown Denver totaled 0.72 inch…but greater amounts likely occurred in other parts of the city.

In 1960…a severe dust devil moving through an Adams County suburban area blew over a fireworks stand…injuring an 11- year-old boy customer and two women operators of the stand. The boy was found under the demolished stand 100 feet away.

In 1961…hail as large as 1 1/4 inches in diameter was reported over east Denver.

In 1967…golf ball size hail fell over portions of metro Denver. Hail stones to 2 inches in diameter damaged roofs and broke windows in northeast Boulder. Marble to golf ball size hail fell at the Boulder airport. A funnel cloud was sighted over the foothills near Boulder. Hail stones of 1 to 2 inches in diameter were measured at Jefferson County Airport near Broomfield. Marble size hail fell in the vicinity of Arvada and Westminster.

In 1982…severe thunderstorms dropped large hail in Denver… Boulder…Commerce City…Lakewood…Wheat Ridge…Golden…and Arvada. Most locations reported hail size from 3/4 to 1 1/4 inches in diameter.

In 1990…the high temperature reached 102 degrees at Stapleton International Airport.

In 1998…hail to 1 1/2 inches in diameter fell near Bennett.

In 2001…the temperature climbed to a high of 101 degrees at Denver International Airport.

In 2012…it was the hottest July on record in Denver since weather records began in 1872. The average temperature for the month was 78.9 degrees which was 4.7 degrees above normal. There were 27 days in which the high temperature equaled or exceeded 90 degrees…which established a new record. There were also 7 days in which the temperature equaled or exceeded 100 degrees which tied the record set in 2005.

In 2016…a severe thunderstorm produced large hail in Castle Rock…ranging in size from 1 to 2 inches in diameter. The hail pummeled neighborhoods as it smashed cars and shattered windows. The storm caused extensive damage to shutters…roofs…siding and fencing.

In 2019…heavy rainfall produced minor flooding near Gold Hill. Severe thunderstorms produced large hail…from 1 to 1 1/4 inches in diameter in Arapahoe and Weld counties.

In 2021…a thunderstorm generated a peak wind gust to 58 mph near Bennett.

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In 1874…a streak of 18 consecutive days of 90 degrees tied for second with another streak that was later set in the summer of 1901. The record of 24 consecutive days was established in the summer of 2008.

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In 1879…a severe hail storm produced considerable damage in the vicinity of Arvada. Some of the stones were unusually large…measuring 6.5 inches in circumference (2 inches in diameter) with an average weight of 1 ounce. The stones were uniformly large with one side concave. The greatest damage was to early wheat…cabbage…and vines. A tree just to the south of the weather station in downtown Denver was struck by lightning. Residents in the house 15 feet away were affected by the strike.

In 1885…thunderstorm winds were sustained to 50 mph in the city.

In 1892…an apparent cold front produced sustained northeast winds to 40 mph with gusts to 45 mph.

In 1955…an apparent microburst wind gust to 69 mph was recorded at Stapleton Airport where the brief strong wind reduced the visibility to zero in blowing dust.

In 1965…hail…up to 2 inches in diameter…struck southwest Adams and northeast Denver counties…damaging cars…windows… And foliage. Hail accumulated up to a foot deep. Wind gusts to 48 mph and hail to 1 inch in diameter fell at Stapleton International Airport where the large hail broke three storm windows and shredded shrubs at the U.S. Weather Bureau upper air building.

In 1968…a pilot reported a tornado 10 miles southeast of Parker.

In 1971…one inch diameter hail stones were reported in Adams County about 30 miles east of Denver.

In 1987…a large tornado touched down 10 miles northeast of Stapleton International Airport. The tornado was vertical and thick and kicked up a large dust and debris cloud. Later…it developed a sinuous rope-like shape as it slowly dissipated. The tornado was visible for 15 minutes. The twister occurred in open country and did only minor damage to a metal shed…porch…and mailbox. A man was killed by lightning in southwest Aurora. He was in his backyard and had a shovel in his hand at the time of the strike. A group of soccer players were hit by lightning on a field in Boulder. A 10-year-old boy was critically injured and hospitalized; fortunately he recovered. Six other people were knocked to the ground by the strike. Two of these were slightly injured. Golf ball size hail fell just east of Littleton and at Highlands Ranch. Hail as large as 3/4 inch in diameter was reported in Aurora and Parker and near Hudson and Franktown.

In 1988…a 45-year-old man was injured by lightning at Cherry Creek Reservoir. Administration of CPR probably saved his life.

In 1990…the temperature reached a high of 100 degrees at Stapleton International Airport.

In 1993…thunderstorm winds blew a roof off a barn near Parker…causing an estimated 15 hundred dollars damage.

In 1994…thunderstorm winds downed power lines in Boulder… Causing power outages. Winds gusted to 66 mph in Boulder… 64 mph in Arvada…and 60 mph in Golden.

In 1998…a small tornado touched down briefly near Barr Lake… But caused no damage.

In 2002…hail as large as 1 3/4 inches in diameter fell in the city of Denver and in Arapahoe County near Littleton. The low temperature of 69 degrees equaled the record high minimum for the date.

In 2006…lightning struck a teenager in Castle Rock as he was mowing his lawn and listening to an iPod. The teen suffered burns to his hands and feet…and had blood running from his ears when he was found. The victim’s eardrums were ruptured…which damaged his hearing. Lightning also struck a house in Castle Rock causing extensive damage to the roof and side of the home. Heavy rains caused flash flooding at Castlewood Canyon State Park near Franktown. The floodwaters destroyed four footbridges along the high trail. A culvert and several roads were washed out in the area. In addition… Two driveways crossing Cherry Creek were washed out near Prairie Canyon Ranch. Heavy rainfall also caused minor flooding on murphy and sand creeks…just east of Buckley AFB. Gun Club Road was closed between Alameda and Mississippi avenues…north of the Murphy Creek Golf Course…where 3 feet of standing water reportedly covered the road. A severe thunderstorm produced large hail to 7/8 inch in diameter in south Aurora near Cherry Creek.

In 2016…a weak landspout touched down briefly in and open field near Bennett.

In 2018…a severe thunderstorm produced a wind gust to 64 mph at Denver International Airport.

In 2021…a severe thunderstorm produced large hail from Brighton to Barr Lake. Hail as large as 1 3/4 inches in diameter was reported.

Continue reading June 30 to July 6: This Week in Denver Weather History →

Weather History

June 23 to June 29: This Week in Denver Weather History

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This Week in Denver Weather History

Late spring and early summer continue Colorado’s severe weather season. Looking back at this week in Denver weather history we see we experience a wide variety of conditions from record-setting heat to damaging thunderstorms with hail, wind and flooding.

From the National Weather Service:

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In 1874…a thunderstorm pelted the city with hail and brief heavy rain. Rainfall was 0.30 inch in 10 minutes. Total rainfall was 0.36 inch for the day. Hail to 1/4 inch in diameter destroyed the strawberry fields near the limits of the city. The thunderstorm dropped the temperature from 93 degrees to 80 degrees in 5 minutes.

In 1887…north winds were sustained to 42 mph.

In 1954…the temperature climbed to a high of 102 degrees… Setting a record for the date.

In 1962…lightning struck and injured a man near Buffalo… southwest of Denver…while he was riding in the back of a pick-up truck. He suffered multiple bruises…cuts…and shock.

In 1965…an apparent tornado was reported 18 miles east of Denver. No damage was reported.

In 1975…hail up to 3/4 inch in diameter fell at Stapleton International Airport and over other parts of metro Denver. Four funnel clouds were sighted: 10 miles northeast of Denver…south of Boulder…southeast of Boulder…and south of Aurora.

In 1976…heavy rain and eroding water collapsed a retaining wall in Thornton.

In 1981…a thunderstorm produced wind gusts to 60 mph in Littleton.

In 1982…two separate bolts of lightning injured three men in southwest Denver. Two buildings were slightly damaged.

In 1987…severe thunderstorms produced large hail across metro Denver. Golf ball size hail fell in Littleton…near Morrison…and in southeast Aurora with 1 1/2 inch hail recorded in south Lakewood and 1 inch hail reported in Littleton…Arvada…and at Cherry Creek dam. Two funnel clouds were sighted 20 miles southwest of Stapleton International Airport.

In 1993…non-convective high winds developed along the Front Range foothills. Wind gusts to 70 mph were common near the foothills with numerous tree limbs broken by the winds. North winds gusting to 36 mph were recorded at Stapleton International Airport.

In 1999…hail as large as 1 inch in diameter was measured in the city of Denver with 3/4 inch hail in Littleton.

In 2001…a severe thunderstorm produced large hail in south metro Denver. Hail as large as 1 1/2 inch in diameter fell in Littleton with 1 1/4 inch hail near Sheridan.

In 2009…hail up to 1 inch in diameter was observed near Parker. At Denver International Airport…a total of 1.64 inches was measured in a 24-hr period…setting a new record for the date.

In 2014…severe thunderstorms produced large hail near Commerce City and Fort Lupton.  The hail sizes ranged from 1 to 1 1/2 inches in diameter.

In 2016…a severe thunderstorm produced a peak wind gust to 60 mph near Strasburg.

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In 1873…there was a great deal of smoke from a fire in the mountains to the southwest of the city during the late afternoon.

In 1875…smoke from forest fires in the mountains to the southwest could plainly be seen from the city.

In 1958…a strong cold front produced a north wind gust to 55 mph at Stapleton Airport where blowing dust briefly reduced the visibility to 1 mile.

In 1982…one inch diameter hail pelted west Denver. A half inch of rain drenched the suburb of Englewood in 10 minutes. Hail piled up to 5 inches deep…snarling rush hour traffic and damaging some stores in a shopping center when the roof started leaking.

In 1988…lightning destroyed the chimney of a house near Evergreen. Another bolt demolished a radio transmitter in the area.

In 1989…golf ball size hail cut a swath 2 1/2 miles wide through open country 14 miles southwest of Bennett. The storm also dropped 1.75 inches of rain on the area. Hail to 3/4 inch in diameter damaged the car of a storm chaser just south of Bennett.

In 1996…a funnel cloud was sighted near Hudson where hail up to 1 3/4 inch diameter fell. Lightning struck a home in Littleton…which sparked a small fire on the roof. Thunderstorm wind gusts to 64 mph were recorded in Castle Rock.

In 2005…severe thunderstorms produced large hail across metro Denver. Hail as large as 1 inch in diameter fell near Castle Rock and Thornton. Hail to 3/4 inch was measured near Northglenn and Fort Lupton.

In 2006…severe thunderstorms raked metro Denver. Hail as large as 2 1/2 inches in diameter shattered automobile windshields in and near Boulder. Hail to 1 3/4 inches pounded areas in and near Lakewood and Morrison. Hail to 1 inch was measured in Wheat Ridge along with 7/8 inch hail in Arvada. Severe thunderstorm wind gusts estimated to 69 mph snapped power lines for a distance of one quarter mile near Castle Rock. Severe thunderstorm winds were measured to 60 mph in Sedalia. Hail as large as 1 inch in diameter fell near Evergreen and Castle Rock. Hail to 3/4 inch in diameter was reported in Louviers and near Conifer.

In 2014…damaging hail…from 1 to 2 inches in diameter… caused extensive damage to homes and automobiles over parts of Arapahoe and Douglas Counties including areas in and near:  Aurora-Cherry Creek…Buckley Air Force Base…Denver International Airport and Parker.  Officially…0.06 inches of rain fell at Denver International Airport…with a peak wind gust of 33 mph from the southeast.

In 2015…two colliding outflow boundaries merged over east Denver and northwest Aurora at the height of rush hour. The collision quickly spawned a severe thunderstorm that produced an EF1 tornado…damaging hail…torrential rain and flash flooding. The tornado touched down in east Denver and west Aurora. The tornado first touched down near Quebec and 6th Avenue. It then moved east northeast across the Lowry Campus into the west part of Aurora. The tornado then lifted near Mount Nebo Memorial Park. Some homes had minor roof damage with one former apartment building on the Lowry Campus had more significant roof damage. The tornado and intense thunderstorm winds uprooted trees…damaging vehicles and blocking roads. The storm produced torrential rain…2 to 2.5 inches…much of which fell in less than 30 minutes and resulted in flooded intersections and power outages. Flash flooding forced the evacuation of a theater at the Cherry Creek Shopping Center…where drifts of hail formed in the parking lot…and flooding set off alarms at the University of Denver`s Ritchie Center. Numerous water rescues were reported as vehicles stalled flooded intersections. Many stoplights were knocked out. The water was reportedly 3 feet deep on the South Broadway ramp to Interstate 25. The bike path along Cherry Creek was inundated with several feet of water at the height of the storm. Ironically…it was “Bike to Work Day”…which made for a long commute home for many.  The South Platte River crested above flood stage for one hour. Employees still at work were urged to stay inside but others waded across flooded intersections downtown. About 30 flights had to be diverted from Denver International Airport.  At Denver International Airport… only 0.05 inches of rain fell.  A peak wind gust to 47 mph was observed from the southeast.

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In 1873…forest fires produced a great deal of smoke in the mountains to the southwest of the city.

In 1958…an unusually cold day for summer set two temperature records for the date. Under cloudy skies with occasional drizzle…a record low maximum temperature of 55 degrees was established along with a record minimum temperature of 42 degrees.

In 1959…a waitress…working at a kitchen sink…was injured by a bolt of lightning…which struck the rear of a tavern in Denver. She was hospitalized.

In 1971…a tornado touched down briefly at a high school football field in Brighton…but caused no damage.

In 1981…3/4 inch hail pelted Wheat Ridge and hail to 1 1/4 inches fell in Louisville. A brief funnel cloud was sighted by national weather service personnel 4 miles east of Stapleton International Airport.

In 1982…a bolt of lightning struck a cabin in the foothills west of Denver. The resulting fire totally destroyed the cabin.

In 1987…golf ball size hail fell near Bennett.

In 1988…a tornado touched down 1 mile south of Watkins and was on the ground for 4 minutes. Another tornado was spotted just southeast of Barr Lake and was on the ground for 5 minutes. No damage was reported from either tornado. Lightning struck two rock climbers near Eldorado Springs. A 25-year-old man was killed…and a 21-year-old man suffered extensive injuries. Thunderstorm winds knocked over two elm trees near downtown Denver. One fell on a house destroying most of it. A nearby building was unroofed…and two cars were damaged. A truck that had been severely damaged by one of the Denver tornadoes 10 days before was hit again. Thunderstorm wind gusts to 51 mph were recorded at Stapleton International Airport.

In 1991…the temperature reached a high of 100 degrees… Setting a new record for the date.

In 1997…one inch diameter hail fell in Arvada and 1 1/2 inch hail in Boulder. Hail as large as 3/4 inches fell in Denver…Louisville…Westminster…and near Broomfield.

In 1999…thunderstorm winds gusted to 58 mph near Fort Lupton toppling an oil rig. A 37-year-old man was killed when he fell 55 feet from the derrick of the rig.

In 2001…four golfers and one construction worker received minor injuries from a nearby lightning strike on the Broadlands Golf Course in Broomfield.

In 2002…hail to 1 inch in diameter was measured in Greenwood Village.

In 2005…hail to 3/4 inch in diameter fell near Bennett and Roggen. A thunderstorm wind gust to 61 mph was recorded near Golden.

In 2009…lightning struck the Darlington Prismatic Electric Fountain in City Park’s lake. The damage was estimated to be approximately $25000.

In 2010…wind gusts associated with a dry microburst downed several trees in the vicinity of 14th and federal…and near Bayaud St. and Clarkson St. In Denver. At Denver International Airport…a peak wind gust to 45 mph was observed from the southwest.

In 2015…severe thunderstorms developed late in the afternoon and continued in the late evening hours. The storms moved over parts of Adams…Arapahoe…Douglas and Weld Counties. The largest hail occurred near Aurora and Keenseburg…with hail up to tennis ball size or 2 1/2 inches in diameter. Elsewhere…the hail size ranged from nickel to half dollar size. At Denver International Airport…just a trace of rainfall was observed.  A peak wind gust of 31 mph was also observed from the east.

Continue reading June 23 to June 29: This Week in Denver Weather History →

Weather History

June 16 to June 22: This Week in Denver Weather History

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This Week in Denver Weather History

Late spring and early summer weather hazards abound in Colorado. Looking back at this week in Denver weather history we see many examples including wildfires, deadly lightning, damaging lightning and dangerous flooding.

From the National Weather Service:

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In 2000…two large wildfires developed in the Front Range foothills as careless campers and very dry conditions proved to be a dangerous combination. Strong winds gusting in excess of 60 mph on the 13th fanned the flames… Spreading both wildfires out of control. Winds gusted to 78 mph atop Niwot Ridge near the Continental Divide west of Boulder. The Hi Meadows wildfire…about 35 miles southwest of Denver…consumed nearly 11 thousand acres and 80 structures…mostly high priced homes. The Bobcat wildfire…located about 12 miles southwest of Fort Collins… consumed nearly 11 thousand acres and 22 structures. Late on the 16th…a strong cold front moved south over the great plains into northeastern Colorado. Low level upslope conditions developed in the wake of the front…producing 2 to 4 inches of snowfall overnight at elevations above 8 thousand feet. Firefighters were able to contain both fires shortly thereafter.

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In 1963…heavy rain and hail ravaged metro Denver. In southeast Denver…heavy rain flooded homes and streets. Hail to a depth of 4 inches on the ground stripped trees and plants and drifted to depths of 3 to 4 feet in some areas. Flood waters on the valley highway were 19 feet deep in places…trapping many cars. Many creeks were running over their banks. On the 15th…the main thunderstorm cell passed over south Denver…dumping as much as 4 inches of rain in 90 minutes. Precipitation at Stapleton Airport totaled 0.91 inch on the 15th and 1.31 inches on the 16th. A funnel cloud was sighted briefly 4 miles to the south-southeast of Stapleton Airport on the 15th. Damage from hail and flooding amounted to near a million dollars.

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In 2021…the temperature in Denver reached 100 degrees for three consecutive days: 101…100…100 respectively. Each established a new record high for the day. It was also the earliest occurrence of such a streak. A record high minimum of 68 also occurred on the 17th.

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In 1950…very heavy rain and hail storms in southwest Denver caused an estimated 750 thousand dollars in hail and flood damage. Thunderstorms produced 2.06 inches of rain at Stapleton Airport with 2.23 inches of rain measured in downtown Denver.

In 1965…a tornado…15 miles south-southeast of Denver… Touched down and damaged two houses in northern Douglas County. Three golfers at a country club and a women who lived north of Castle Rock were injured by falling structures.

In 1983…a microburst wind gust to 54 mph was recorded at Stapleton International Airport.

In 1984…a tornado touched down briefly in Parker. No damage was reported.

In 1986…lightning injured 5 people just north of the Denver city limits in Adams County. The victims were members of a drum and bugle corps and were standing near a metal scaffold. Heavy rain from the storm also caused street flooding in the metro area.

In 1991…hail to golf ball size fell at Conifer.

In 1992…a rare mid-June high wind event wreaked havoc over metro Denver when a pacific cold front moved across the Rocky Mountains. Strong winds at speeds of 40 to 50 mph were common along the Front Range foothills. Winds reaching 107 mph in the foothills west of Denver and 79 mph at Longmont…caused damage ranging from trees being toppled to large trucks being rolled over. Strong winds estimated at 75 mph rolled a 35-foot truck carrying building supplies on U.S. Highway 36 north of Boulder. The truck driver and a passenger as well as the driver of another car were slightly injured. The winds downed power lines. The gambling towns of central city and Blackhawk were without power for a couple of hours. West winds reached 43 mph at Stapleton International Airport.

In 1996…a small tornado touched down in the foothills southwest of Boulder near Pinecliffe…knocking down 50 to 100 large pine trees. A house nearby sustained damage when shingles were ripped from the roof. The tornado also picked up a 17-foot sailboat with attached trailer and carried it 25 feet into a nearby tree. In addition… Thunderstorm wind gusts to 46 mph were measured at Denver International Airport.

In 2004…hail as large as 1 inch in diameter fell near Castle Rock. Hail to 3/4 inch was measured near Bennett.

In 2005…severe thunderstorms produced hail as large as 1 inch in diameter in Centennial.

In 2011…severe thunderstorms produced and damaging across parts of metropolitan Denver. In Lakewood…a tree blew down and landed on at least five cars. At Centennial Airport…a section of a roof on a hangar was ripped off the strong winds. A peak wind gust of 46 mph was recorded at Centennial Airport and Denver International Airport in the evening.

In 2022…severe thunderstorms produced large hail across parts of Boulder and Weld counties. The hail ranged from 1 to 1 1/2 inches at Allenspark…Ft. Lupton…Hudson and Lochbuie.

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In 1965…on the afternoon and evening of the 16th…violent thunderstorms produced extremely heavy cloudbursts of rain over the palmer divide and sent a wall of water as high as 20 feet down both branches of Plum Creek into the South Platte River and through metro Denver. The heavy rainfall produced the most devastating flood in the history of Denver. Rainfall totaled 14.0 inches in 3 hours at both Larkspur and Palmer Lake with 12.0 inches recorded in Castle Rock. The flood waters caused extensive damage to roads and bridges in larkspur…Castle Rock…and Sedalia…including washing out the I-25 bridge over East Plum Creek in Castle Rock. The citizens of metro Denver received reports of the flooding to the south and had a few hours to initiate evacuation procedures along the South Platte River…greatly limiting the loss of life. By evening…the flood reached Littleton where a heroic effort was made to save nearly 150 horses at the Centennial Racetrack…which was completely inundated by the flood waters. As the flood proceeded through the city of Denver…the river became more than 1/2 mile wide and destroyed all homes…trailer courts… And businesses in its path. The waters contained debris ranging from refrigerators to old cars. As many as 26 bridges were damaged or destroyed…including the 6th Avenue freeway bridge across the South Platte. Both Public Service Company power plants were shut down by the flood. The King Soopers grocery chain bakery was inundated. About midnight… The torrent crested at 25 feet above normal with flow exceeding 40 times normal and is the record flood on the South Platte and many of its tributaries. The flood caused 230 million dollars in damage and 8 deaths along the entire South Platte River basin. The intense rain also caused flooding along Cherry Creek in Denver…on Toll Gate and Sand Creeks in east metro Denver…and on Kiowa and Bijou creeks to the east of Denver. The South Platte River flood closed nearly every major east-west highway into Denver…nearly isolating the city. The flood caused heavy damage to state and county roads in the area. Railroads were also hard hit with the main yards in lower downtown inundated. Sewerage… Water supply facilities…and irrigation works also received heavy flood damage. The flood crest did not reach Nebraska until the 20th.

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In 1915…northwest winds were sustained to 41 mph with an extreme velocity to 42 mph.

In 1967…this was the 24th consecutive day with a trace or more of precipitation from May 25th. Precipitation totaled 5.87 inches during the period…more than a third of the average yearly total.

In 1975…hail more than 2 inches in diameter fell in eastern Aurora.

In 1977…golf ball size hail was reported 3 miles east of Arapahoe County airport…now Centennial Airport. Heavy hail to 3/4 inch in diameter was reported in Littleton… Castle Rock…and Sedalia.

In 1979…a man and a girl were struck and killed by lightning while walking in a park in northwest Denver.

In 1987…3/4 inch hail fell near Boulder.

In 1991…a microburst wind gust to 59 mph kicked up some blowing dust at Stapleton International Airport.

In 1998…hail as large as 3/4 inch in diameter fell in Boulder.

In 2003…lightning struck a feeder line…knocking out the electricity to about 3000 residents in Littleton. A lightning strike caused minor damage to the roof and attic of a home in Lafayette. Another lightning strike caused minor roof damage to a residence in Louisville. Yet another lightning strike hit a home in Denver and caused a small attic fire. Hail as large as 1 inch in diameter was measured near Centennial Airport and near Greenland.

In 2009…hail up to 1 inch in diameter was measured near Longmont.

In 2015…a severe thunderstorm produced hail up to 1 1/2 inches in diameter near Arapahoe Park…and up to 1 inch in diameter near Parker.

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In 1964…high winds at speeds of 50 to 60 mph with gusts as high as 75 mph caused damage to homes…power lines…and trees in Boulder. Non-convective west winds gusting to 46 mph caused some blowing dust at Stapleton International Airport on the 17th.

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In 1875…a windstorm produced sustained winds to 45 mph during the morning hours. Numerous forest fires along the base of the mountains were visible from the city.

In 1886…northwest winds sustained to 40 mph were the strongest of the month that year.

In 1987…severe thunderstorms produced lightning…large hail… A tornado…heavy rain…and strong winds across metro Denver. Rainfall totaled 2.50 inches in an hour in Wheat Ridge… Causing minor flooding. I-25 was flooded in north-central Denver…snarling traffic. Hail 7/8 inch in diameter fell in Louisville with 1 1/2 inch hail near Golden and 1 to 1 3/4 inch hail in and near Castle Rock. A tornado touched down briefly in Castle Rock. No damage was reported. Lightning started a small fire that burned half a cabin near Evergreen.

In 1994…a funnel cloud was sighted over Aurora; hail to 1 3/4 inch diameter fell near Brighton; and hail over an inch in diameter fell over Aurora…southeast Denver… Louisville…and Boulder. Lightning struck a home in Henderson 9 miles north of Denver and knocked a hole in the roof…which caused the ceiling to collapse. Hail to 1 1/4 inch diameter was measured at Stapleton International Airport.

In 2002…the Hayman wildfire in the foothills to the southwest of Denver intensified…and the winds aloft carried the smoke plume directly over metro Denver…again creating a dense haze of smoke which blocked the sun. Surface visibilities were again reduced to as low as 1 1/4 miles at Denver International Airport.

In 2004…severe thunderstorms produced hail to 3/4 inch in diameter near Morrison…in Littleton…near Conifer…near Castle Rock…and in Aurora near Cherry Creek.

In 2013…a landspout tornado touched down at DIA. The tornado sent 10 thousand travelers on the concourse…on planes and in the terminal scrambling to get into tornado shelters. The tornado formed just to the south of Runway 35R and then moved slowly northwest between Runway 35R and 35L…and moved to within one third of a mile of Concourses A and B before dissipating. The tornado moved extremely close if not over the ASOS (Automated Surface Observation System) and another low level wind shear sensor at DIA. The ASOS weather observing system reported a 97 mph wind gust…while the wind shear sensor reported a wind gust to 109 mph at the same time indicative of an EF1 tornado. There was only minor damage noted to the equipment. Nine flights were diverted elsewhere during a tornado warning. Severe thunderstorms also produced large hail up to quarter size in Adams and Weld Counties.

In 2014…a severe thunderstorm produced large hail up to quarter size near Buckley Air Force Base. At Denver International Airport…a peak wind gust to 55 mph was observed from the southwest…along with 0.37 inches of water.

In 2015…a severe thunderstorm produced hail…from quarter to half dollar size…near Lafayette…Louisville and Superior.

Continue reading June 16 to June 22: This Week in Denver Weather History →

Weather History

June 9 to June 15: This Week in Denver Weather History

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This Week in Denver Weather History

June means severe weather in Colorado and our look back at this week showcases that fact. Numerous, historical events have occurred during this week in the past including the disastrous Hayman fire and the infamous 1988 Denver tornadoes.

From the National Weather Service:

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In 1979…rain…at times with thunder on the 7th…fell almost continuously through the morning of the 9th. Rainfall totaled 2.28 inches at Stapleton International Airport over the 3 days. High temperature of only 49 degrees on the 8th was a record low maximum for the date.

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In 1900…an apparent cold front produced north winds to 42 mph with gusts to 47 mph.

In 1923…heavy rainfall totaled 2.18 inches in downtown Denver…where northwest winds were sustained to 27 mph. Heavy rain also fell in Boulder…causing flooding on Boulder and south Boulder creeks.

In 1939…post-frontal sustained northwest winds to 35 mph produced some blowing dust…which reduced the visibility to one mile at times during the afternoon. Dusty conditions prevailed into the early evening. The airport station reported a maximum wind of 56 mph. A few minor injuries and some damage resulted. A few trees were uprooted…some fruit was blown from trees…and a section of power lines was blown down.

In 1959…dry thunderstorm winds…estimated to near 70 mph… Toppled a 40-foot-high poplar tree…which was 4 to 5 inches in diameter…near Cherry Creek dam. The Colorado state patrol reported a possible tornado 1 mile south of the dam.

In 1960…strong gusty winds tore the roofs from 2 patios in Aurora. One of the roofs was blown over a house and landed on a car damaging its top. A house trailer was also overturned. Other minor damage was reported to roofs… Windows…and trees in Aurora. A thunderstorm wind gust to 43 mph was recorded at Stapleton Airport.

In 1963…golf ball size hail fell at Cheery Creek Reservoir.

In 1967…a small tornado damaged trees and a dwelling in south Denver. The storm touched down at the intersection of 1st Avenue and Harrison Street and moved northeast to the intersection of 3rd Avenue and Albion Street. Damage included 3 small roofs removed…15-20 large trees uprooted…one car overturned and thrown against a house… Plus other minor damage. A funnel cloud reported at the same time 10 miles north of Denver possibly touched ground. Later…funnel clouds were reported 12 miles south-southeast of Stapleton International Airport…10 miles southwest…and 5 miles north. A tornado was sighted 3 1/2 miles east of Stapleton International Airport by weather bureau personnel for a duration of 5 minutes. Heavy rain and some hail fell over much of the area.

In 1974…the start of the shortest seasonal snow free period on record…94 days…occurred with the last snow of the season…a trace…on the 8th. The first snow of the next season occurred on September 11th when a trace of snow fell at Stapleton International Airport. A funnel cloud was observed just east of Aurora and a small funnel was sighted just northeast of Stapleton International Airport.

In 1985…a thunderstorm wind gust to 62 mph was reported at Golden Gate Canyon in the foothills west of Denver.

In 1986…a thunderstorm…which dumped heavy rain and caused some street flooding across north metro Denver…produced a small tornado 5 miles east of Brighton. No damage was reported.

In 1987…strong thunderstorm wind gusts in Conifer destroyed a porch on a house; the wind gust apparently picked up the porch and dropped it on a man…killing him. The wind also damaged the roof of the house and a nearby barn. The same thunderstorm spawned a tornado…which touched down briefly just south of Lakewood. No damage was reported. Up to 3 inches of rain fell in a short time 8 miles southwest of Littleton. A few businesses in Englewood suffered minor water damage. A tornado was sighted between Watkins and Bennett. It was on the ground for 15 minutes. A weak tornado also touched down 4 miles southwest of Castle Rock. The twister tossed an aluminum shed into the air and carried it about 100 feet. A funnel cloud was sighted 15 miles east-northeast of Stapleton International Airport.

In 1988…golf ball size hail fell in Conifer along with 1.30 inches of rain. Three miles north of Louisville…1.10 inches of rain fell in 20 minutes. Ping pong ball size hail was measured in Arvada.

In 1990…3/4 inch hail fell in Castle Rock.

In 1991…hail two inches in diameter fell near Evergreen. Hail to 1 inch diameter fell in Lakewood where a funnel cloud was also sighted. One inch diameter hail was also reported in Aurora.

In 2002…high temperatures…low relative humidities…and strong gusty winds allowed the Hayman wildfire…located in the foothills to the southwest of Denver…to become the largest wildfire in the state’s history. Although the fire was initially started by a U.S. Forest Service employee…the ongoing drought and dry conditions allowed the fire to spread rapidly out of control. The wildfire consumed nearly 138 thousand acres of forest land and 133 homes before it could be contained and finally extinguished on June 30th. About 1800 households had to be evacuated during the blaze. Southwest winds aloft swept the smoke plume directly over metro Denver…creating poor air quality and blocking the sun. Much of metro Denver choked on smoke with the southern suburbs receiving the most. Smoke and ash restricted surface visibilities to a mile or less at times in the Denver and Castle Rock areas and to 2 miles at Denver International Airport.

In 2003…thunderstorm winds gusted to 51 mph at Denver International Airport. The storm produced only a trace of rain.

In 2004…severe thunderstorms produced large hail across portions of metro Denver for the second day in a row. The most extensive damage occurred across southern sections of metro Denver in Aurora…Lakewood…Littleton…and south Denver. The combined damage to homes and vehicles…not including commercial buildings…was estimated at 146.5 million dollars…making the event the 4th costliest insurance disaster in the state’s history. Hail as large as 2 1/4 inches in diameter fell near southern Aurora with hail to 1 3/4 inches in the city of Denver and in Lakewood. Hail to 1 1/2 inches fell near Morrison with 1 inch hail measured in Thornton…near Buckley Air Force Base…and near Roggen. Hail to 3/4 inch diameter fell in Littleton and near Conifer. A small tornado touched down near Bennett…but did no damage.

9-10

In 1864…high water from melting snow combined with heavy rains over the upper reaches of the South Platte River forced the river over its banks and caused flooding of low lying areas along the river in the city. The amount of rainfall in the mountains and in the city is unknown.

10

In 1943…a man was killed by lightning while using a surveying instrument at Buckley Field.

In 1969…hail stones 2 to 3 inches in diameter caused extensive damage to buildings and automobiles in an area from northeast of Boulder to Longmont. Two funnel clouds were reported near Castle Rock. A funnel cloud and 1 inch hail stones were reported 10 to 20 miles southeast of Stapleton International Airport. Hail stones to 1 3/4 inches fell 3 miles west of Littleton. Hail to 3/4 inch diameter fell over southeast Denver.

In 1988…thunderstorm winds clocked to 60 mph unroofed a porch and downed a fence at a home near Stapleton International Airport. A small tornado touched down briefly in northeast Aurora. Another small tornado touched down for 3 minutes in southeast Aurora. No damage was reported from either twister.

In 1989…a National Weather Service observer saw lightning strike 2 storage tanks at 40th and Havana…3/8 mile northeast of Stapleton International Airport. The strike temporarily knocked out some weather observing equipment at the National Weather Service.

In 1991…a tornado was sighted 2 miles south of Castle Rock. No damage was reported. The funnel cloud associated with the tornado was sighted for 5 minutes by national weather service observers at Stapleton International Airport.

In 1994…lightning struck a home in Denver…which started a fire in the attic and caused minor damage.

In 1997…lightning struck a security guard at the castle pines golf course near Castle Rock. He received only minor injuries.

In 1999…severe thunderstorms rolled off the foothills over metro Denver…producing large hail and damaging winds. Hail to 1 inch diameter fell near Evergreen with 1 3/4 inch hail measured west of Golden. Hail to 1 1/2 inches fell in Commerce City with one inch hail in Lakewood…Wheat Ridge… The city of Denver and at Denver International Airport where thunderstorm winds gusted to 58 mph. As the storms moved east…3/4 inch hail was reported in Aurora…and damaging thunderstorm winds developed between Bennett and Strasburg. Winds gusting as high as 69 mph blew half a metal roof from a shed in a Bennett lumberyard. A small barn was also leveled between Bennett and Strasburg. Winds also gusted to 58 mph near Manilla.

In 2000…a dry microburst produced a wind gust to 58 mph at Jefferson County Airport. Thunderstorm winds gusted to 55 mph at Denver International Airport.

In 2003…hail as large as 1 3/4 inches was measured at Centennial Airport and near Parker.

In 2005…hail to 7/8 inch in diameter was reported near Parker with 3/4 inch hail measured near Castle Rock.

In 2009…lightning struck an apartment complex…a veterinary hospital in Boulder and caused minor damage. Lightning also struck two oil tanks…one in Boulder and the other at Front Range airport north of Watkins. The oil tanks in both instances were set on fire and suffered extensive damage.

In 2010…a complex of severe thunderstorms hammered portions of eastern Arapahoe…eastern Douglas and western Elbert counties. The hail ranged from 1 inch to 3 inches in diameter. The largest hail was observed near Elizabeth. Areas in and around Aurora…byers…Parker and Thornton were also impacted by large hail. One weak tornado touched down near prospect valley but did no damage. At Denver International Airport…a peak wind gust to 35 mph was observed from the northwest.

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In 1882…heavy thunderstorm rains on the morning of the 10th caused a rapid rise in Dry Creek…which enters the South Platte River at Fairview in present day south Denver. This…combined with additional heavy rainfall on the 11th caused the South Platte River to overflow. Five people drowned and several houses were destroyed. Total losses in the city and suburbs was estimated at 75 thousand dollars. Total rainfall in central Denver was 2.21 inches over the 2 days.

In 2013…the high temperature of 99 degrees on the 10th broke the previous record maximum temperature of 97 for the date. Also…the minimum temperature of 68 and high temperature of 100 degrees on the 11th established a new record for highest minimum and maximum temperature for the date.

Continue reading June 9 to June 15: This Week in Denver Weather History →

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