As we near the end of July the weather in Denver tends to be a bit more stable. That doesn’t mean the severe weather threat disappears as can be seen at our look back at this week in Denver weather history. Particularly notable are lightning injuries and deaths, flash flood events and even tornadoes.

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.

22

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.

22-23

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.

24

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 2016…severe thunderstorms produced damaging straight-line. A storm leveled a greenhouse and caused tree damage near Byers. A peak wind gust to 74 mph was measured at Denver International Airport.

24-25

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.

25

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.

26

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.

26-27

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.

27

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 Piccadilly 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.

27-31

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.

28

In 1882…intense thunderstorm lightning struck a number of places in the city…but no significant damage was reported.

In 1910…heavy thunderstorm rainfall totaled 2.21 inches in downtown Denver. Rainfall was 1.11 inches in an hour during the early afternoon.

In 1922…heavy rainfall to the south of Denver caused Cherry Creek to rise to the top of the retaining walls in the city. The creek did not flood; however…the large volume of water discharged into the South Platte River did inundate a few blocks of Globeville. Flooding also occurred along bayou creek near Franktown to the south of the city.

In 1923…thunderstorm winds were sustained to 38 mph with gusts to 52 mph.

In 1957…iridescent cirrocumulus clouds of unusual formation and brilliant color…oriented from southwest to northeast over metro Denver…were sighted by U.S. Weather Bureau observers at Stapleton Airport shortly after noon.

In 1966…heavy rains from a severe thunderstorm caused flash flooding on deer creek…southwest of Littleton. A child was injured when washed from a car caught in the flood waters. The flooding damaged property along the creek. Strong winds damaged several houses in suburban Littleton.

In 1970…a microburst wind gust to 52 mph was recorded at Stapleton International Airport.

In 1974…a tornado was sighted just east of Buckley Field in Aurora. No damage was reported.

In 1982…up to 2.50 inches of rain drenched an area just southwest of Denver in 30 minutes. This was the second day of heavy rain across portions of metro Denver.

In 1984…1.25 inches of rain fell in 45 minutes in Arvada. Minor flooding occurred on Bear Creek after a small dam broke.

In 1989…lightning killed two men in Arvada. They were taking wash from a clothesline when a bolt hit the older man…39… Killing him instantly. The bolt then traveled along the line…which was stretched between 2 tall trees…and hit his 26-year-old brother who died the next day.

In 1996…several weak tornadoes developed along a thunderstorm outflow boundary that moved into southern weld…northern Jefferson…and Adams counties. The tornadoes sighted near Bennett…Barr Lake…and in Arvada caused little damage. Strong thunderstorm winds downed several trees in the city of Denver and toppled several trees 7 miles west of Arvada where shingles were blown off several houses. Thunderstorm wind gusts reached 58 mph in Broomfield.

In 1997…a weak tornado touched down briefly in Parker…damaging a greenhouse. Twenty pieces of the fiberglass roof were ripped away. Heavy rainfall in the foothills washed out some culverts in the pine and conifer areas. Heavy rainfall spread over the plains with 4 to 7 inches reportedly falling near Hudson. Several County roads were washed out between fort lupton and Hudson. Several basements in the area were flooded up to the ceiling. Standing water…up to 3 feet deep…was reported in some backyards. Later in the evening…a flash flood killed 5 people and injured 40 others in two mobile home parks in Fort Collins. The torrential rainfall also caused extensive damage on the Colorado State University campus. Thunderstorm rainfall totaled 0.80 inch at Denver International Airport and 1.09 inches at the site of the former Stapleton International Airport.

In 1999…heavy rainfall…up to 3 inches an hour…triggered a massive rock and mudslide along I-70 near Bakerville. The slide area was about 200 feet wide and 20 feet deep. Several other smaller slides were also reported along the highway. As a result…I-70 was closed for nearly 25 hours in both directions until the debris could be cleared from the roadway. The blockage of I-70 was one of the longest in the history of the highway in Colorado. A severe thunderstorm produced a wind gust to 64 mph at Denver International Airport. The storm also produced 1.56 inches of rain and briefly reduced the visibility to 1/4 mile.

In 2004…a severe thunderstorm produced hail as large as 1 inch in diameter in Thornton.

In 2010…a wet microburst produced very heavy rain and torrential hail in Boulder County…in the vicinities of caribou…Nederland and eldora. Flash flooding washed out sections of County roads 126 and 128 near caribou. Several large Boulders had fallen across the roadways. Considerable flooding was reported in Nederland. Water was also observed running across County road 130…between Eldora and Nederland. The hail had accumulated up to 8 inches deep near Eldora. Several vehicles were stuck in the ice…forcing the temporary closure of CR130 and the Lake Eldora Ski Road until snowplows could clear away the hail. Lightning strikes caused minor damage to two local businesses in Nederland. At Denver International Airport…a thunderstorm produced 0.30 inches of rain along with a peak wind gust to 38 mph.

In 2012…a tornado touched down briefly at the southeast corner of Mt. Evans near Lincoln Lake. The estimated elevation where this tornado touched down was near 12500 feet. This would make this tornado one of the highest ever observed in the U.S.

In 2014…two weak landspouts touched down; one near Ft. Lupton and the other on the southwest side of the Rocky Mountain Arsenal Wildlife Refuge. No damage was reported. A strong thunderstorm wind capsized a boat in Barr Lake. All three occupants made it to shore with no injuries.

In 2016…severe thunderstorms in western Adams and east central Jefferson Counties produced large hail near Lakewood…Golden and South Glenn. The hail ranged from quarter to ping pong ball size.

28-30

In 1889…dense smoke from forest fires in the mountains obscured the sun over the city for three days.

In 1971…a vigorous cold front late on the 28th produced northeast wind gusts to 39 mph and record breaking cold temperatures on the 29th and 30th. The temperature dipped to 47 degrees on the 29th and 43 degrees on the 30th… Setting record minimums for the dates. Upslope cloudiness along with rain and fog early on the 29th helped set a record low maximum temperature of 58 degrees for the date.