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:
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.
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.
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.
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.
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.
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.
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.
In 1874…a severe thunderstorm during the late afternoon produced 1.36 inches of rainfall in an hour…most of which fell in 20 minutes. There was much damage from flooding of streets and considerable damage to private property. The lightning was brilliant and continuous during the storm. Seven buildings were struck by lightning in the city…in addition to many places where it struck only the ground. A magnificent example of ball lightning was observed. When about 200 feet above the house tops…the ball exploded and broke into 7 or 8 different balls…each about 6 inches in diameter. Upon reaching about 20 feet above the ground…these balls broke into small fragments about 3 inches long and 1/2 inch wide. A shed situated in an alley about one block away was literally covered with these sparks. After the storm was over…the shed and adjacent area showed no trace of the event. Not the slightest mark could be detected on structures or on the ground.
In 1879…a terrific electrical storm passed over the city during the afternoon. The lightning display was unusually vivid and the crash of thunder seemed at the very house tops. A few homes and buildings were struck by lightning. A home on Capitol Hill sustained much damage to furniture… But the residents in another wing of the house were not injured. Lightning struck a fence at the corner of Curtis and Broadway. A lightning bolt stunned a workman and knocked a mason’s trough from his hand. A school was struck but was not damaged. Lightning struck the ground near tenth and Colfax. Rain fell in torrents for a time…but the heaviest was on the outskirts of the city. Rainfall in the city was only 0.30 inch.
In 1882…lightning struck and killed a man in the northern part of the city.
In 1895…heavy rainfall of 1.53 inches was measured in downtown Denver.
In 1931…the high temperature reached 100 degrees in downtown Denver.
In 1965…lightning struck and killed a boy standing by an automobile near Stapleton International Airport. Scattered heavy showers accompanied by hail and wind occurred across metro Denver. Heavy rain caused some street damage in Commerce City.
In 1973…minor thunderstorm wind damage was reported in Aurora.
In 1983…heavy thunderstorms dumped torrential rain and large hail across metro Denver. The most serious problems were caused by heavy rainfall in the foothills…which produced flooding on bear creek. Runoff from 3 inches of rain in 45 minutes at Kittredge caused Bear Creek to rise 5 feet in 10 minutes at Morrison…washing out two bridges. One bridge collapsed…plunging a fire truck into the water…but the occupants were not injured. The town was evacuated for 2 hours. Evergreen was drenched with 2.61 inches of rain in 30 minutes…which caused street flooding along with power outages. Hail to golf ball size damaged cars. A deck on a house east of Evergreen was washed away. At Idaho Springs… 2 inches of rain fell in 45 minutes. Golden received 3 inches of rain in an hour with 0.80 inch of rain in seven minutes at Littleton. Heavy rain and large hail also fell in the city of Denver and its northern and eastern suburbs… Causing street flooding. Water was 6 feet deep on one Aurora street.
In 1991…heavy rains caused extensive flooding across north metro Denver. Ralston Creek in Arvada flowed out of its banks. At the intersection of I-25 and I-70…up to 8 feet of water covered the highway. A foot of water covered a stretch of I-70 in northwest Denver. Thunderstorm rainfall totaled only 0.82 inch at Stapleton International Airport.
In 1998…lightning sparked a fire which caused extensive damage to a home in Englewood. Most of the second floor was destroyed.
In 2004…severe thunderstorms produced hail to 1.25 inches in diameter in Commerce City and near Brighton.
In 1991…heavy rains over the Palmer Divide and along the Front Range caused the South Platte River to flood from near Henderson to Fort Lupton. The river was out of its banks at several locations with water covering the roads through the night. Only minor damage was reported.
In 1901…the temperature climbed to a high of 90 degrees… Marking the 18th consecutive day with a high temperature of 90 degrees or more. This equaled the record of 18 consecutive days set from July 1st through July 18th in 1874.
In 1910…the temperature climbed to a high of 101 degrees in downtown Denver.
In 1936…the high temperature reached 100 degrees in downtown Denver.
In 1957…a tornado was observed by National Weather Service personnel 25 miles east-northeast of Stapleton Airport for 7 minutes. No property damage or injuries were reported. The public reported a funnel cloud 10 miles northeast of Brighton.
In 1960…lightning struck many locations across metro Denver. A Boy Scout leader was struck and injured at the Rocky Mountain Arsenal. Some sections of Arvada were blanketed with a white layer of hailstones. A number of weed fires were started by lightning. Some houses were struck…but no serious damage occurred. Heavy rain fell from northwest Denver to Brighton with up to 1.50 inches in some areas.
In 1965…heavy rain flooded and damaged homes in Georgetown… Where the sewer system was damaged and the water supply contaminated. Heavy rains in Aurora washed out earthen bridges over Sand Creek. Streets were flooded in Denver. Several highways were washed out to the east and southeast of Denver.
In 1975…heavy rains caused flash flooding in the foothills west of Denver. Several roads and businesses were damaged in the central city and Blackhawk areas.
In 1983…heavy thunderstorms blasted Denver and areas to the south. Douglas County was hardest hit. Golf ball size hail fell in and near Parker. Many homes at the Pinery south of Parker had windows broken and paint stripped by the storm with some vehicles dented by the large stones. In Parker… 1.90 inches of rain fell in just 30 minutes. Many roads in Douglas County were washed out…and at least one bridge was damaged. Up to 2 inches of rain fell in Lakewood…and Littleton was drenched by 1.60 inches in 15 minutes. A department store in Lakewood suffered water damage when a pipe handling runoff broke…sending 4 inches of water onto the floor of the store.
In 1990…a thunderstorm wind gust to 53 mph was recorded at Stapleton International Airport…where 1/8 inch diameter hail fell.
In 1992…heavy thunderstorm rains caused Howard Gulch in southeast Denver to flow over its banks. A weather spotter recorded thunderstorm wind gusts to 63 mph in Aurora. Another spotter measured a wind gust to 60 mph…which toppled a large tree. Thunderstorm winds gusted to only 41 mph at Stapleton International Airport.
In 1996…hail…as large as an inch in diameter…fell 5 miles west of Castle Rock.
In 1997…damaging thunderstorm winds associated with a wet microburst ripped the roof off a barn near Brighton… Causing the east side of the structure to collapse. The roof of a nearby utility shed was also lifted off and blown 60 feet away. West winds gusted to 38 mph at Denver International Airport.
In 2001…a severe thunderstorm pelted Littleton with hail as large as 1 1/2 inches. Total damage to vehicles…roofs… Buildings…and landscaping totaled over 600 thousand dollars. Rain leaked into offices…damaging computers. Almost every vehicle parked in the Littleton center lot sustained some hail damage. Thunderstorm winds gusted to 55 mph at Denver International Airport.
In 2002…a small tornado briefly touched down near Bennett. No damage was reported.
In 2004…heavy thunderstorm rainfall in the overland fire burn area caused flash flooding in Jamestown. Up to a foot of water reportedly covered the highway near Jamestown. Many of the town’s culverts filled with dirt and debris… Causing the overflow to wash onto streets and into homes. Heavy machinery had to be used to remove piles of mud up to 7 feet deep. Parked cars slid down the street with the mud and water…and many had to be dug out. The fire station in Jamestown was inundated with 10 inches of muddy water. Heavy thunderstorm rainfall caused street flooding in Federal Heights and Thornton. Several streets were inundated with 2 to 4 feet of water…including 84th Avenue and Grant Street…Conifer Street and Huron Blvd…. 102nd Ave. and Melody…as well as 83rd Ave. and Washington. Several cars were stranded in the flood waters. Heavy rainfall also caused street flooding in parts of Westminster. Water reportedly flowed into car windows just north of 104th Avenue and U.S. Highway 36. Sections of two roads had to be closed due to flooding. Heavy thunderstorm rainfall of up to 2 inches in 45 minutes caused flash flooding just east of Aurora. Floodwaters ranging from 2 to 3 feet deep forced the closure of Powhaten…Gun Club and Picadilly roads. Lightning caused power outages in parts of Arvada. About 9800 customers were without power for up to 90 minutes.
In 1896…heavy cloudbursts in the foothills west of Denver caused flash flooding on bear creek…clear creek…Golden gate gulch…and Mount Vernon Creek…resulting in a total of 27 deaths. The downpour dislodged large Boulders…one of which crushed a house. The heavy rain also caused a dam on cub creek to wash out…adding even more water to the flood. A wall of water as high as 10 feet flooded Evergreen and passed down Bear Creek…washing away many structures along the way. The flood crest produced 3 feet of water in downtown Morrison during the early evening. Flash flooding on Mount Vernon Creek added to the flooding in Morrison. In Golden…the flooding washed out bridges on Clear Creek and on Cresman and Tucker gulches and forced the closure of the power plant. In Denver…a thunderstorm produced hail of unknown size during the afternoon and rainfall of 1.23 inches overnight.
In 1958…a thunderstorm wind gust to 52 mph was recorded at Stapleton Airport.
In 1965…heavy rain caused flooding on clear creek and tucker gulch in Golden and west Denver. Damage in Golden was estimated at 80 thousand dollars. Heavy rain south of Denver washed out temporary earthen bridges constructed following the June floods in Castle Rock…Littleton… Englewood…and Denver. Bear creek in south Denver reached flood stage. A cloudburst on Cub Creek in Evergreen washed out bridges and roads. Heavy rain fell over all the Denver and Aurora areas…causing some flooding of roads…streets… And bridges. A man drowned in a flooded irrigation canal near Hudson. Heavy rain caused flooding of streets and roads in Blackhawk and Central City. Hail caused minor damage in Idaho Springs.
In 1967…seven bridges were washed out along a normally dry creek bed south of State Highway 7 west of Brighton. One car was washed into the creek when a bridge gave way.
In 1970…hail stones to 1 1/4 inches in diameter fell in the foothills of Jefferson County southwest of Denver.
In 1971…golf ball size hail was reported in foothill areas of Jefferson County west of Denver. A funnel cloud was sighted in Aurora. Wind gusts estimated at 60 mph…hail… And heavy rain up to an inch in 15 minutes caused local flooding and some other damage in several areas of metro Denver. Hailstones to 3/4 inch in diameter fell 7 miles southeast of Denver.
In 1973…a thunderstorm wind gust to 52 mph was recorded at Stapleton International Airport where one inch diameter hail was measured.
In 1981…strong winds downed a power line in northeast Denver. Wind gusts to 50 mph were recorded at Chatfield Reservoir.
In 1987…3/4 inch diameter hail fell 5 miles northeast of Commerce City.
In 1996…hail…up to 1 3/4 inches in diameter…fell at Chatfield Reservoir. Hail to 3/4 inch in diameter was measured near Bennett.
In 2000…lightning struck near two golfers at Ute Creek Golf Course near Longmont…knocking them to the ground. The men received only minor injuries.
In 2001…lightning from a thunderstorm knocked out electrical power to about 1500 residents in the city of Denver.
In 2004…a chilly day with fog and thunderstorms resulted in two temperature records. The low temperature of 49 degrees was a record minimum for the date. The high temperature of only 58 degrees was a record low maximum for the date.
In 2003…maximum temperature of 100 degrees on the 24th was a record high for the date. Low temperature of 73 degrees on the 25th was a record high minimum for the date.
In 1875…brief heavy rain and hail lasted only 5 minutes… But the 1/4 inch diameter hail covered the ground to a depth of 1/2 inch and made the streets look like there had been snowfall. There was much crop damage…especially to corn…and some sheep were killed. Precipitation totaled 0.51 inch in the city.
In 1896…a heavy thunderstorm produced sustained northwest winds to 45 mph with gusts to 50 mph and 1.02 inches of rain.
In 1965…a cloudburst dumped 1.99 inches of rain in 30 minutes at Stapleton International Airport. The storm was accompanied by strong winds gusting to 70 mph. The heavy rain flooded numerous streets in east Denver and Aurora. One inch diameter hail accompanied a cloudburst…9 miles southwest of Denver. A funnel cloud was sighted 25 miles northwest of Denver. In Aurora…there were unofficial reports of 2.30 inches of rain in 40 minutes and 3.30 inches of rain in 30 to 40 minutes. Rainfall totaled 2.05 inches at Stapleton International Airport. Rainfall of 2.42 inches for 24 hours on the 24th and 25th was the second greatest on record for July.
In 1977…a tornado touched down briefly in Aurora southeast of Cheery Creek Reservoir. No damage was reported. A funnel cloud was sighted for 4 minutes by national weather service personnel 10 miles north of Stapleton International Airport near Henderson.
In 1991…heavy rain…up to half an inch in 10 minutes…caused flooding in Westminster…Northglenn…and north Denver where a section of railroad track was washed away. At Stapleton International Airport…heavy thunderstorm rain totaled 1.85 inches and briefly reduced the visibility to 1/4 mile. Hail to 1/8 inch in diameter was also measured. A tornado touched down briefly near Fort Lupton. No damage was reported.
In 1998…heavy monsoonal thunderstorm rains caused flooding and flash flooding in eastern and southern sections of metro Denver…including Englewood and Aurora…when about 2 to 3 inches of rain inundated the area. Both I-25 and I-70 were closed for 2 to 3 hours as several low lying areas became impassable due to the high waters. The water was estimated to be 15 feet deep in one flooded underpass along I-25. As a result…the freeway was closed from south of 6th Avenue to University Blvd. Standing water forced the closure of I-70 at gun club road east of Denver. In Englewood…U.S. Highway 285 was closed…when high water made it impassable. Several cars were reportedly floating down the roadway near Sheridan Blvd. In Aurora…the intersection at Yale Ave. and Chambers Rd. was flooded by high water up to 4 feet deep when a spillway on the High Line Canal was breached. Lightning also knocked out 11 transformers across metro Denver…causing several small fires and scattered power outages. Flood and flash flooding also occurred north of Strasburg when as much as 2.51 inches of rain fell in an hour. The deluge resulted in considerable flooding of local streets and county roads. Torrential rainfall of 2 to 3 inches in less than an hour triggered a flash flood in Virginia Canyon. County Road 279 between Idaho Springs and Central City was closed for two days to clear debris from mudslides. Several cars in Idaho Springs were washed off the road…and numerous basements were flooded in town. Thunderstorm rainfall totaled 2.69 inches at Denver International Airport.
In 2001…lightning struck two homes in Lafayette…damaging the roof and attic of one and shorting out the electrical system in another. Hail to 1 3/4 inch in diameter was measured 7 miles north of Castle Rock with 3/4 inch hail 7 miles north of Sedalia.
In 2005…heavy thunderstorm rain in the vicinity of the Overland wildfire burn scar triggered a mudslide in Jamestown. Rocks the size of bowling balls…along with silt and mud slid down the mountain into the town. No one was injured. One parked car was buried by the debris.
In 2006…heavy thunderstorm rainfall caused flash flooding 1 mile north of the town of Westcreek in southwestern Douglas County. Several maintenance roads were washed out by the floodwaters.
In 1891…a thunderstorm produced sustained northeast winds to 44 mph with gusts to 60 mph and 0.16 inch of rain.
In 1894…a thunderstorm produced sustained southwest winds to 36 mph with gusts to 58 mph…but only 0.04 inch of rain.
In 1910…the high temperature reached 100 degrees in downtown Denver.
In 1959…a Denver man was stunned while standing by a car that was struck by lightning. He was treated for burns and shock at a local hospital. Thunderstorm winds gusted to 55 mph at Stapleton Airport.
In 1983…two heavy thunderstorms hit the northern and western suburbs. The first drenched Northglenn with an inch of rain in 30 minutes. The second storm dumped an inch or more of rain in Idaho Springs and Evergreen. The heaviest rainfall… 2.90 inches in an hour…caused minor street flooding in Golden.
In 1984…heavy early morning thunderstorms drenched the foothills southwest of Denver. Rainfall to 1 1/2 inches in just 30 minutes occurred between Evergreen and Conifer. In nearby Turkey Creek Canyon…1.80 inches of rain was recorded in 35 minutes.
In 1985…a long rope-like white tornado touched down 5 miles east of Erie and stayed on the ground…mainly over an open field…for 18 minutes. However…the twister damaged a few cars on I-25 and injured 3 people from broken glass. The storm flipped over a van…blew out car windows…and ripped a highway sign. It also blew an outbuilding off its foundation. A tornado also touched down briefly 8 miles north of Bennett. No damage was reported from this storm.
In 1988…a 9-year-old girl was slightly injured by lightning in Parker.
In 2003…a severe thunderstorm in and south of Franktown produced hail as large as 1.75 inches in diameter
In 1885…heavy cloudbursts on the palmer divide south of Denver caused flooding on Cherry Creek in the city overnight. The high water washed away street and railroad bridges and a few houses. The flood waters completely inundated the rail yards in lower downtown. This was the worst flood on Cherry Creek since May 19-20…1864…but the damage was mitigated by stream improvements and fewer structures near the channel. There was also no simultaneous flood on the South Platte River to slow the flow of water through the city. Rainfall in the city was only 0.08 inch on the 26th.
In 1897…an apparent dry microburst produced sustained west winds to 48 mph with gusts to 60 mph and a trace of rain.
In 1901…a thunderstorm produced north winds to 38 mph with gusts to 41 mph and rainfall of only 0.01 inch in downtown Denver. This was the only measurable rainfall of the month… Making this the driest July on record.
In 1953…an unconfirmed tornado in south Lakewood touched down briefly and abruptly dissipated. No damage was reported from the twister.
In 1955…the public sighted a funnel cloud estimated at 500 feet above the ground near the western edge of Lowry Field. Wind estimates up to 60 mph were reported in the vicinity.
In 1956…a severe thunderstorm produced 3/4 inch diameter hail and wind gusts to 48 mph at Stapleton Airport where rain fall totaled 1.08 inches.
In 1965…a tornado was sighted 21 miles south of Denver in Douglas County. No damage was reported.
In 1977…a thunderstorm wind gust to 51 mph was recorded at Stapleton International Airport. A funnel cloud was sighted by an aircraft east of Parker.
In 1982…heavy rain doused Boulder with 1 1/2 to 3 inches of rain over a short period of time…causing extensive street flooding.
In 1984…strong thunderstorms drenched several areas. Rainfall of 1.04 inches occurred in just 20 minutes at Boulder. Downpours also hit Aurora and northeast Denver… Delaying flights at Stapleton International Airport for an hour. Up to 3/4 inch of rain fell in central Aurora in 15 minutes.
In 1989…lightning hit a home in Littleton…setting a bed on fire. Damage was confined to the bedroom.
In 1994…lightning struck a furniture store in Boulder… Igniting a fire which caused major damage to the building and contents.
In 1997…lightning sparked a fire…causing extensive damage to a home in Watkins. Heavy rain caused Lena Gulch to surge 2 feet over its banks in Golden. The fire department had to rescue a man when his van stalled in high waters. High waters from swollen creeks and streams washed out bridges and several sections of road in southeast Aurora. A 200-to-300 foot section of road was washed away where Picadilly Street dips across Coal Creek. Three youths had to be rescued when they became stranded by rapidly rising water in another normally dry creek bed.
In 1999…lightning was suspected of igniting a fire which caused substantial damage to a farm in Hudson. The blaze destroyed a 10-foot by 60-foot metal pole barn…a pick-up truck…a SUV…a boat and trailer…3 four wheeler vehicles… And other farm equipment.
In 2007…a man was struck and killed by lightning while jogging at Matthews Winters Park in Morrison.
In 1956…96 percent of the total precipitation for the month of July occurred over the last five days of the month. Heavy thunderstorms produced 4.00 inches of rainfall at Stapleton Airport. This amount of precipitation in 5 days or less had been exceeded only 3 times in previous record. The last time had been in December of 1913 as snow. Considerable property damage occurred across metro Denver from flooding.