Our look back at this week in Denver weather history reminds us that severe weather can continue to strike, even during what is normally a relatively calm month. Lightning, hail and flooding are three continuous threats as we see during our look back at history this week.

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. This was one day short of equaling the all time record. The record of 18 consecutive 90 degree or above days was first set from July 1st through July 18th…1874. The record was equaled from July 6th through July 23rd…1901.

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.

4-5

In 1875…nearly every railroad running into the city was damaged by heavy thunderstorm rains. The heavy rains washed out wooden bridges over normally dry creeks. Some trains were entirely suspended. In the city…heavy thunderstorm rain totaled 1.05 inches on the 4th…but only 0.28 inch on the 5th.

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.

5

In 1908…a late evening thunderstorm produced sustained north winds to 40 mph…hail…and 0.45 inch of precipitation.

In 1949…a dust devil…possibly a small tornado…was observed 3 miles to the northwest of Stapleton Airport.

In 1973…the temperature reached 100 degrees at Stapleton International Airport.

In 1974…strong thunderstorm winds damaged a mobile home…a barn…two houses…and several sheds near Watkins.

In 1975…a thunderstorm wind gust to 53 mph was recorded at Stapleton International Airport. Hail up to 3/4 inch in diameter fell over the northwest suburbs and in northwest Denver.

In 1977 three houses in Denver were struck by lightning. Some heavy damage and fire occurred.

In 1990…lightning caused minor damage to houses in Castle Rock…Louviers…and Littleton.

In 1996…lightning caused only minor damage when it struck a home in Evergreen. Lightning from a fast moving thunderstorm blasted a large hole in the side of a house in Lakewood. Lightning triggered a minor power outage in the Boulder area. About 200 homes were affected.

In 2001…severe thunderstorm winds gusted to 60 mph at Denver International Airport and to 70 mph…7 miles southwest of the airport.

In 2008…microburst winds downed a large tree and some power lines near a Denver apartment complex. Several of the tenants’ vehicles were damaged.

In 2009…a wet microburst produced very strong winds in and just east of Denver.  A peak wind gust of 69 mph was measured 1.5 miles east of Denver.  In addition…1.50 inches of rain fell in 30 minutes.  A peak wind gust to 68 mph was also observed near byers.  Southwest winds gusted to 31 mph at Denver International Airport.  The airport also received 0.30 inches of rainfall.

6

In 1876…the high temperature reached 101 degrees in downtown Denver.

In 1943…four people were injured by lightning in Denver during a severe early evening thunderstorm. At least two houses were set on fire by the lightning. One house had 1500 dollars in damage and the other 1000 dollars.

In 1959…wind and lightning caused some damage in metro Denver. Wind gusts to 67 mph blew down power lines…signs… And trees. Lightning struck several transformers…leaving many areas without power.

In 1971…a microburst wind gust to 68 mph was recorded at Stapleton International Airport.

In 1973…the temperature reached a high of 103 degrees. This was the second consecutive day with a temperature of 100 degrees or more.

In 1984…a weak tornado moved through eastern Aurora. About 10 homes sustained minor damage to roofs; some sections of fence were thrown more than a block. Soft hail…an inch in diameter…fell over central Aurora…and 1.35 inches of rain fell in just 45 minutes…5 miles east of Buckley Field. Torrential rain and hail stopped traffic on I-225 in central Aurora for 15 minutes. Street flooding was widespread. A wind gust to 57 mph was recorded in southeast Aurora. A wind gust to 66 mph was reported at Front Range airport near Bennett. Northwest winds gusted to 44 mph at Stapleton International Airport where only 1/8 inch hail fell.

In 1986…one inch diameter hail fell near Conifer in the foothills west of Denver. The storm produced 1.50 inches of rain in an hour with a storm total of 2.15 inches. Nearby buffalo creek was drenched with 0.80 inch of rain in just 10 minutes.

In 1996…3/4 inch diameter hail fell in Bennett…east of Denver. Hail…as large as 1 1/2 inches in diameter… Damaged several vehicles in the parking lot of the Colorado Speedway race track near Dacono north of Denver. Several trees were also damaged.

In 2001…a severe thunderstorm wind gust to 59 mph was recorded at Denver International Airport…along with small hail.

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

In 2010…heavy rain caused flash flooding near interstate 70 at the Byers exit.  Two feet of water was observed moving across the bottom of exit ramp.  One car was washed into a tree but no one was injured.  In addition…severe thunderstorms produced hail up to 1 1/2 inches in diameter near Franktown.  At Denver International Airport…only 0.01 inches of rainfall was observed.  A peak wind gust to 45 mph from the west was also recorded.

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 recorded 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 2012…heavy rain produced flash flooding in Boulder County near Jamestown. James Canyon Drive was closed after heavy rain washed out a section of the roadway. Heavy rain washed out a section of Magnolia Road…east-southeast of Nederland. Nearby…a trained spotter 4 miles east-northeast of Nederland… Measured 2.20 inches of rainfall. Flash flooding was also reported in the Fourmile burn area along Summerville Road. In Dacono…in southern Weld County… The Colorado Department of Transportation used snowplows to clear standing water…up to 6 inches deep…from a section of Interstate 25. The interstate was closed in both directions for nearly two hours. South of the Denver…in central Douglas County… Flash flooding was reported near Perry Park…where 2.5 inches of rain fell in one hour.

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.

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.

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.

9-10

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

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

10

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

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

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

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

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

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

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

In 2000…three children were injured…one critically…when lightning hit a nearby tree at panorama point atop flagstaff mountain just west of Boulder. Lightning hit the tree…entered the ground…then struck the children. Lightning sparked a grassfire that burned about 50 acres at the rocky flats environmental test facility. Also… Lightning sparked at least 6 fires in the Hudson and Keenesburg areas as thunderstorms…accompanied with heavy rain…large hail…and tornadoes…moved through southern Weld County. Over 2 inches of very heavy rain caused flooding along an I-76 exit ramp near Keenesburg. The fire department rescued 15 stranded motorists as high water inundated sections of the exit ramp and adjacent highway. Basements were also flooded in Keenesburg. One home reportedly had 7 feet of standing water in the basement before the rain subsided. A weak tornado (f0) touched down briefly near Brighton…but caused no damage.

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

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

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

11

In 1872…heavy rainfall started at 4:00 pm and continued into the night. The heavy rainfall damaged homes and buildings in all parts of the city. Rainfall totaled 1.64 inches.

In 1888…the temperature reached 100 degrees in downtown Denver.

In 1954…the high temperature climbed to 102 degrees at Stapleton Airport.

In 1970…a girl walking in a park in southeast Denver received eye and facial injuries when lightning struck nearby. Lightning also caused numerous power outages and heavy rainfall produced local flooding at several locations across metro Denver.

In 1974…large hail up to 1 1/2 inches in diameter fell in Thornton.

In 1990…the worst hailstorm in American history in terms of dollar damage at the time battered metro Denver. Storm damage totaled 605 million dollars…as it cut a 5-to 10-mile wide swath from just southeast of Estes Park to northeast of Colorado Springs. Hail as large as baseballs (2.75 inches) pounded metro Denver. Hardest hit areas were southeast Boulder County…the Jefferson County Airport in Broomfield… Arvada…east Wheat Ridge…southwest and south-central Westminster…west Thornton…northwest…west-central and downtown Denver…northeast and east-central Lakewood…just east of Littleton…portions of Arapahoe County west of I-25… And northern and central Douglas County near Castle Rock and Franktown. Golf ball to baseball size hail severely damaged roofs on thousands of homes and buildings…battered tens of thousands of automobiles…windows…signs…street lights…and traffic signals…stripped paint…awnings…and trim from buildings…punched holes in the roofs of two homes in Arvada…knocked out power and telephone service to thousands of homes and businesses…defoliated thousands of trees…ripped up greens and fairways on a number of golf courses…and severely damaged several aircraft tied down at Jefferson County airport. Hail the size of baseballs fell for several minutes in old town Arvada. Later…golf ball size hail and heavy rain pummeled two northwest Denver amusement parks. Hardest hit was Elitch Gardens amusement park where 47 people were injured and received treatment for bumps…cuts…and bruises at local hospitals. Many of the injured were stranded on rides during the storm when power failed. Hail clogged storm sewers…causing rain water to back up 3 to 6 feet deep on some roads and intersections in Arvada. Several basements were flooded. In some places hail was washed into drifts several feet deep. In addition… The storm spawned 2 small tornadoes. One touched down briefly in Lakewood near 6th Avenue and Kipling Blvd….but did no damage. In Castle Rock…a tornado (f1) did heavy damage to some homes and vehicles in the Founders Village development near Ridge Road.

In 2001…lightning struck two homes in Thornton. Most of the damage was confined to the attics of both homes. Hail as large as 3/4 inch in diameter fell in Keenesburg…Longmont… And near Boulder.

In 2015…a peak wind gust to 55 mph was measured from the northwest at Denver International Airport. A trace of rainfall was also observed.

11-12

In 1872…heavy rain from 4:00 pm until 2:00 am caused much damage. Rainfall totaled 1.76 inches.