Thornton’s workweek starts off with mild temps, some smoke above

A pretty good looking Monday ahead for us. We will see temps a bit below normal and only a slight chance for thunderstorms but with some smoke above.

Sunny skies will be the rule for most of the day. It will, however, be hazy as smoke from wildfires in Canada and Pacific Northwest arrive. This afternoon we have just the slightest chance for a thunderstorm. Highs will top out in the mid-80s.

Tonight, skies will be mostly clear with the smoke lingering above. Lows will be around the 60-degree mark.

July 21 to July 27: This Week in Denver Weather History

This Week in Denver Weather History

As we continue in what is the hottest time of the year, we also begin to enter the monsoon season. Our look back at this week in Denver weather history shows that this can bring a wide range of severe weather. Most common are heavy rains which can lead to flooding but dangerous and damaging lightning and hail and even tornadoes are possible.

From the National Weather Service:

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.

18-2

In 1987…a streak of 16 consecutive days of 90 degrees ranked 4th on the list of hot streaks. The record of 24 consecutive days was established in the summer of 2008.

19-23

In 2005…the high temperature climbed above 100 degrees on each of the 5 days with readings of 101 on the 19th…105 on the 20th…104 on the 21st…and 102 on both the 22nd and 23rd. A new record maximum temperature for the month of July of 105 degrees was set on the 20th…which also equaled the all-time record maximum for Denver of 105 degrees first set on August 8th in 1878. Daily maximum temperature records were set on each day…and the 5 day period equaled the record for the most consecutive days of 100 degrees or more first set from July 4th through 8th in 1989. The intense heat resulted in a high use of electricity for cooling purposes. The demand for electric power exceeded the supply and rolling black-outs… Each lasting about an hour…were scheduled across metro Denver during the afternoons and early evenings.

20-23

In 1961…unusually cool weather for July resulted in several temperature records. Record minimum temperatures were set or equaled on each day with readings of 51…51…49… And 49 degrees. High temperature of only 64 degrees on the 21st was a record low maximum for the date.

20-25

In 1965…heavy showers and thunderstorms doused metro Denver with significant rain each day. Rainfall for the six days totaled 5.16 inches at Stapleton International Airport. Massive rainfall occurred on the 20th…21st…and 25th… Flooding streets and basements and causing streams to overflow. The heaviest rainfall…2.05 inches…at Stapleton International Airport occurred on the 25th.

21

In 1879…lightning struck a house in north Denver. The bolt struck the center of the roof driving part of it into the house and scattered shingles all over the yard. Furniture in the house was heavily damaged…but none of the nine residents were injured other than being stunned. The noise sounded as if a cannon had been exploded. Rainfall was only 0.02 inch downtown.

In 1921…northwest winds were sustained to 42 mph with gusts to 48 mph.

In 1943…a severe thunderstorm during the evening caused the death of a man whose truck skidded on a muddy roadway on a steep hill and overturned pinning him underneath. Several small fires were started by the lightning…and electrical wires were downed. No serious property damage was reported… But firemen answered 19 alarms in 2 hours. One person was injured by lightning.

In 1965…a funnel cloud was sighted in the northern portion of Denver. Later…4 or 5 funnel clouds were sighted about 15 miles north of Stapleton International Airport. Heavy rain accompanied by hail washed away part of a city street and caused other flooding in central city. There were heavy showers and some damage from lightning in both Denver and Boulder. Marble to golf ball size hail fell 10 miles northwest of Stapleton Airport.

In 1966…heavy thunderstorm rains flooded streets and basements across metro Denver.

In 1973…a tornado touched down briefly 2 miles northeast of Parker…causing minor damage. Funnel clouds were also sighted 3 miles northeast of Sedalia…11 miles south southeast of Stapleton International Airport…and near Parker. Hail to 3/4 inch in diameter fell over the western suburbs of Denver.

In 1974…heavy thunderstorm rains caused flash flooding in metro Denver. Rainfall totaled 1.26 inches at Stapleton International Airport.

In 1976…heavy thunderstorm rains occurred across south metro Denver with 1.75 inches of rain recorded in 40 minutes in southeast Aurora and 2.00 inches in 20 minutes at Cheery Creek Reservoir. A funnel cloud was sighted by the public east of Arapahoe County airport…now Centennial Airport.

In 1981…the temperature reached 100 degrees…setting a new record high for the date.

In 1983…downpours drenched the Front Range where amounts of 1 to 2 inches were common. The heaviest reported rainfall was 2.36 inches in a 6-hour period at Parker where hail to 3/4 inch and wind gusts as high as 75 mph occurred. Up to golf ball size hail fell in the Parker and Castle Rock areas; wind gusts to 75 mph were recorded in Castle Rock.

In 1993…thunderstorm winds toppled a 3 story high Russian olive tree in Boulder. The tree barely hit and only slightly damaged a parked car.

In 1995…thunderstorm winds from the west gusted to 55 mph at Denver International Airport.

In 2002…heavy thunderstorm rainfall caused flash flooding in the Hayman fire burn area. South Deckers Road…State Highway 126…was closed when 4 feet of water inundated a section of the roadway. The U.S. Forest Service had to remove 40 truckloads of sediment to reopen the road. Also…heavy debris flow washed out a secondary service road in southwest Douglas County. Hail as large as 3/4 inch in diameter fell near Bennett.

In 2011…lightning struck a home in Arapahoe County and caused substantial fire damage. Five people were in the home but no one was injured. There was structural damage to both the interior and exterior of the residence.

22 Continue reading July 21 to July 27: This Week in Denver Weather History

Thornton Weather’s weather station is nearing its end of life

The time is coming… Our Davis Instruments VP2+ weather station has served us well for 17+ years. Sadly, despite many parts replacements, it is showing its age and we are going to need to get a new unit soon.

As this is a professional-level weather station to ensure accuracy and reliability, you can imagine it is not cheap. Normally we would not ask this but, in the past, our supporters’ donations have helped us maintain and upgrade the station and we are hoping you might consider helping us keep Thornton’s longest running, most reliable weather station going.

To learn more, please see here.

Thornton’s weekend starts out toasty but cooler temps, good chances for thunderstorms await

Friday offers up conditions like we saw for much of the week with very warm temps and a chance for thunderstorms. We then cool down Saturday and Sunday and see better chances for precipitation.

For today, mostly sunny skies will be above in the morning then, as usual, cloud cover increases in the afternoon. Highs will top out right near the average high for the date of 91 degrees. The afternoon brings a good chance for thunderstorms with gusty winds and brief, heavy rain being possible. Tonight, storm activity will ease after sunset and skies will be mostly clear. Lows will be in the low 60s.

Saturday sees us cool down a good bit with highs in the mid-80s expected. With increased moisture aloft, partly sunny skies will be above. We may see a sprinkle of rain early then the afternoon will offer up some scattered thunderstorms. Saturday night, cloud cover lingers and lows dip around 60 degrees.

Sunday will be the coolest day of the three day period and bring the best chance for precipitation. It will be mostly cloudy and highs will reach the low 80s. A bit of rain will be possible in the morning then chances increase in the afternoon, particularly late afternoon and evening.

Have a great weekend!

Thursday sees temperatures climb a bit, just a chance for a PM thunderstorm

The mercury will climb a few degrees today to a bit above average. Thunderstorm activity will also decrease but we still have a chance.

Following the same pattern of recent days, mostly sunny skies start us off then cloud cover increases in the afternoon. High temperatures will be in the low 90s.

The afternoon and evening bring only scattered thunderstorm activity. The best opportunity comes in the late afternoon.

Tonight, any thunderstorm activity will wrap up by about 10:00pm. Skies will then be mostly clear and lows dip to the low 60s.

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.

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

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

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

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.

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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.

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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

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, natural disasters & climate news and information.