August 30 to September 5 – This week in Denver weather history.
As always, when looking at weather history we are reminded of the varied and sometimes dangerous weather conditions we have here in Colorado. Our look this week we see high temperatures soaring to 97 degrees but also we see the earliest snowfall on record.
From the National Weather Service:
19-30
In 1875…grasshoppers appeared in great numbers at 10:00 am on the 19th. Thousands landed on the ground. The streets were literally covered with them. Swarms of grasshoppers were seen on each day. All gardens in the city were devastated…and in the countryside the grasshoppers were very destructive to ripened grain. On the 30th the grasshoppers were so numerous as to almost darken the sun.
30
In 1981…60 mph winds were reported in Boulder.
In 2004…a severe thunderstorm produced hail as large as 1 inch in diameter in south Aurora near Cherry Creek.
31
In 1951…hail as large as 1 3/4 inches in diameter caused an estimated 300 thousand dollars damage in metro Denver. Hail as large as 1 1/2 inches in diameter was measured at Stapleton Airport.
In 1978…strong thunderstorm winds tore the roof off an apartment building in Aurora…downed trees…and damaged windows in Denver. A microburst wind gust to 58 mph was recorded at Stapleton International Airport.
In 1985…a thunderstorm wind gust to 60 mph was clocked at Buckley Field in Aurora.
In 1997…hail to 1 1/4 inches in diameter was measured in Aurora.
In 2006…a female postal worker was struck and injured by lightning while delivering mail in Westminster.
In 2008…lightning struck a home in Brighton…damaging the roof and a bedroom. The damaged totaled 20 thousand dollars.
August 23 to August 29 – This week in Denver weather history
Quite the interesting week in Denver weather history. Swarms of grasshoppers are the most unusual item we see but there is plenty of standard severe weather including tornadoes, landspouts, hail, lightning and much more.
From the National Weather Service:
19-30
In 1875…grasshoppers appeared in great numbers at 10:00 am on the 19th. Thousands landed on the ground. The streets were literally covered with them. Swarms of grasshoppers were seen on each day. All gardens in the city were devastated…and in the countryside the grasshoppers were very destructive to ripened grain. On the 30th the grasshoppers were so numerous as to almost darken the sun.
22-24
In 1987…some locations in metro Denver had a total 3-day rainfall of 2 to 4 inches. Rainfall totaled 0.96 inch at Stapleton International Airport.
23
In 1900…northwest winds were sustained to 42 mph with gusts to 49 mph.
In 1921…a thunderstorm cloudburst produced 2.20 inches of rainfall in an hour over downtown Denver. This is the greatest 1 hour rainfall on record at the official observing site in the city. Precipitation totaled 2.93 inches…which is the greatest calendar day precipitation ever recorded in august.
In 1941…one man was killed by lightning about 2 miles from the official weather station in downtown Denver.
In 1962…a home near Boulder was destroyed by a lightning- caused fire.
In 1968…strong winds buffeted Boulder briefly during the early morning hours. At the National Center for Atmospheric Research…winds averaged 55 mph with gusts to 85 mph. Damage was minor. Northwest winds gusted to 31 mph at Stapleton International Airport.
In 1977…lightning damaged at least 6 homes in Aurora.
In 2008…a landspout touched down near Westcreek in Douglas County. One man was seriously injured when he tried to escaped several falling trees in his ATV. One of the trees struck his back and broke two vertebra. Another camper narrowly escaped injury. Seconds after he back up his truck…a tree came down where it had been parked.
August 16 to August 22 - This week in Denver weather history
August is usually considered one of the calmer weather months in Denver but as our look back in weather history for this week shows, that isn’t always the case. Thunderstorms and all their associated dangers – lightning, flooding, tornadoes and more – all present a very real danger even this time of year.
From the National Weather Service:
16
In 1902…a thunderstorm produced west winds sustained to 48 mph with gusts to 60 mph…but only a trace of rain.
In 1952…a thunderstorm wind gust to 50 mph was recorded at Stapleton Airport.
In 1960…lightning struck a warehouse in central Denver… Causing 8 thousand dollars in damage to the building and stored electrical equipment.
In 1975…large hail…1 1/2 to 1 3/4 inches in diameter…fell about 4 miles north of Castle Rock. Hail caused some minor damage in Aurora. A funnel cloud was reported 25 miles east of Denver near Bennett.
In 1981…a tornado touched down briefly in open country just to the east of Aurora. No damage was reported.
In 1982…a thunderstorm wind gust to 61 mph was recorded at Buckley Field in Aurora. At the same time almost an inch of rain flooded and closed streets in south Aurora. A women was hit by lightning just north of Denver. A house in the area was also struck.
In 1985…a thunderstorm produced strong wind gusts over southern metro Denver. One strong wind gust hit Cheery Creek Reservoir…capsizing a boat and drowning a man. The wind gusts…clocked as high as 50 mph…also downed a few trees.
In 1989…1 3/4 inch diameter hail fell at Intercanyon in the foothills of Jefferson County.
In 1990…lightning caused minor damage to a south Aurora home. No injuries were reported.
In 1994…strong thunderstorm winds caused damage in southern Weld County near Hudson and Fort Lupton. Two mobile homes were destroyed and a few lost their roofs. Up to 20 downed power poles and the destruction of two 115 thousand-volt towers caused widespread power outages. Thunderstorm gust front winds from the north gusted to 48 mph at Stapleton International Airport.
In 2000…lightning ripped most of the roof from a home in southeast Aurora. The bolt sparked a fire which destroyed the residence. Damage was estimated at 250 thousand dollars.
In 2002…the temperature climbed to a maximum of 100 degrees setting a new record high for the date.
In 2003…a teenager was injured when he was struck by lightning while camping at Herman Lake…13 miles northwest of Georgetown. The boy was knocked unconscious and suffered minor injuries.
16-19
In 1979…heavy thunderstorm rains on each of 4 consecutive days dumped a total of 2.62 inches of rain on Stapleton International Airport. The heaviest rain…1.05 inches… On the 19th was accompanied by 1/4 inch diameter hail.
August 9 to August 15 - This week in Denver weather history
Denver and Colorado as a whole are known for their unusual weather. This week in particular is notable for one extraordinary event in weather history – clouds of grasshoppers!
8-10
In 1979…heavy thunderstorm rains on each of three consecutive days dumped a total of 2.22 inches of rain at Stapleton International Airport. The heaviest rain… 0.95 inches…fell on the 9th. Small hail to 1/8 inch diameter fell on the 8th.
8-13
In 1875…clouds of grasshoppers were seen flying through the air on the prevailing winds during each day.
9
In 1900…a thunderstorm produced west winds sustained to 47 mph with gusts to 55 mph…but only 0.01 inch of rain.
In 1902…a thunderstorm produced no rain and north winds sustained to 52 mph with gusts to 60 mph.
In 1934…heavy cloudbursts in the foothills near Kittredge and at the head of Mount Vernon creek caused flash flooding on both bear creek and Mount Vernon Creek at Morrison… Which resulted in 6 deaths and much property damage. The highway in Mount Vernon Canyon was destroyed by the flood waters.
In 1981…3/4 inch hail fell at Kittredge near Evergreen in Jefferson County.
In 1987…3/4 inch hail fell in Boulder and 9 miles northwest of Castle Rock.
In 1995…lightning struck a 16-year-old counselor in the back of the head while he and a friend were standing under a tree at the singing river ranch…7 miles west of Evergreen. He stopped breathing…but his friend was able to summon help and they were able to revive him. He was hospitalized for a few days and released.
In 1998…brief…weak tornadoes (f0) were sighted near Bennett and Roggen. No damage was reported. Hail as large as 1 inch diameter fell in Franktown with 3/4 inch diameter hail measured near Castle Rock. Thunderstorm winds gusted to 61 mph near Roggen.
August 2 to August 8 - This week in Denver weather history
On first glance our look at this week in Denver weather history appears to be less eventful than many we have looked at previously. However, the severity of the events that appear on the historical weather calendar this week are enough to make you stand up and pay attention. While August is typically a pretty quiet weather month, it is clear that severe weather can certainly strike and Thornton is mentioned in more than one significant event.
From the National Weather Service:
2
In 1878…the high temperature reached 100 degrees in downtown Denver.
In 1911…an apparent dry microburst produced sustained west winds to 42 mph.
In 1972…one workman was killed and another injured when a strong gust of wind destroyed a partially completed apartment building in south Denver. Hail to 1 3/4 inch diameter fell in Golden.
In 1973…hail to 3/4 inch diameter was reported in Boulder.
In 1986…a major outbreak of severe thunderstorms occurred along the Front Range. Thunderstorms developed explosively. Some places were hit by large hail twice. Two inch diameter hail broke car windows on I-25 west of Brighton…and up to 1 1/4 inch hail broke windows in Thornton. Baseball size hail damaged several planes near Watkins. Funnel clouds were sighted around Aurora. Hail over 1/2 inch in diameter covered the ground 3 to 4 inches deep at Hudson northeast of Denver. Most of the hail fell north of metro Denver…but 3/4 inch diameter hail was measured at Stapleton International Airport. Total damage from the hail storms this day was estimated at over 10 million dollars.
In 1991…late afternoon thunderstorms produced heavy rain across metro Denver. Two feet of water covered parts of I-25 in southeast Denver…while one foot of water covered parts of U.S. Highway 285 in Englewood. Thunderstorm rainfall totaled 0.50 inch at Stapleton International Airport.
In 2001…severe thunderstorms producing heavy rain and hail… Either washed out or damaged several County roads in the Watkins and Bennett areas. A small tornado (f0) touched down near Bennett…but did no damage. Hail as large as 1 3/4 inches in diameter fell near Watkins. One inch diameter hail was measured near Hudson and Keenesburg.
In 2008…strong winds blew several trees down in Denver… Damaging homes and downing power lines. A peak wind gust of 67 mph occurred at Centennial Airport…with gusts to 60 mph estimated in Denver. A peak wind gust of 37 mph was measured at Denver International Airport. An elderly man was killed when a wind damaged tree broke free and crushed him while he attempted to remove it. The downed power lines caused outages to about 500 Xcel energy customers.
July 26 to August 1 - This week in Denver weather history
Weather can be deadly – we are all well (hopefully) aware of that. Looking at this week in Denver weather history we are reminded of that and the tragedy that weather can bring to our state. We see numerous cases of lightning causing death and injury but no one incident highlights the dangers of weather more than what occurred on July 31, 1976. The Big Thompson Flood was Colorado’s worth weather-related disaster and claimed 144 lives. More details on all these events are below.
13-5
In 2008…a streak of 26 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.
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.
July 19 to July 25 - This week in Denver weather history
This week in weather history we really begin to see the arrival of monsoon season and the heavy rains and flooding it can bring to the Thornton and Denver area. Be sure to check out the events on the 23rd and what the heavy rain brought to the Thornton area in 2004.
13-5
In 2008…a streak of 26 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.
18-19
In 2003…heavy rain producing thunderstorms caused flash flooding across southern metro Denver. Automated rain gages measured 2 to 3 inches of rain in less than an hour. The heavy rainfall caused many intersections and underpasses to flood…stranding motorists. Sections of I-25 and I-225 were closed due to the high water.
19
In 1875…recent heavy rains produced high waters on many creeks and rivers in the area…which threatened the destruction of property at some locations. Cherry Creek in the city was running the highest in 10 years. Heavy rain in the mining regions over the last 2 days resulted in water running “everywhere” and the suspension of some work.
In 1881…a thunderstorm passing across the city produced lightning with no rain. A woman was seriously injured when struck by lightning several blocks from the weather office in downtown Denver.
In 1934…the temperature reached a high of 100 degrees in downtown Denver.
In 1965…hail…rain…and lightning hit west metro Denver. Hail stones as large as 1 1/2 inches in diameter accumulated to a depth of 2 inches in Evergreen where 2.95 inches of rain in 2 hours caused some flooding in the business section of the town. Lightning caused some power outages.
In 1973…two funnel clouds were observed 5 miles southeast of Littleton. The same funnel clouds were observed for 20 minutes…5 miles west and 5 miles west-southwest of Arapahoe County airport…now Centennial Airport.
In 1975…lightning injured a man in Denver and caused power outages in Aurora…Lakewood…Westminster…and west Denver.
In 1984…strong thunderstorm winds gusting to 45 mph shattered 7 large plate glass windows at Stapleton International Airport.
In 1985…a tornado touched down in the surrey ridge area of northern Douglas County…just west of I-25. Ten homes were damaged; one under construction was nearly destroyed. Two vehicles were thrown off I-25 injuring three people. A pick-up truck was thrown 50 feet by the twister. In addition…a cluster of severe thunderstorms pounded all of metro Denver with torrential rain…hail…and wind. The heaviest rain fell in Aurora where one location reported 2.37 inches in just 40 minutes. One location in northeast Aurora received a total of 4.30 inches from the storm. There was extensive street and basement flooding…and a number of roads were damaged or washed out. An Aurora boy suffered minor injuries when he was washed into a drainage ditch. Golf ball size hail in Aurora piled up to 5 inches deep. An inch of rain fell in 20 minutes at Stapleton International Airport…closing it to air traffic for an hour. Up to 1 1/2 inches of rain fell in just 15 minutes over central Denver with the high water closing I-25. The water was so deep on the freeway…that one vehicle was completely submerged and people were diving into the water from the freeway overpass. Three homes in Littleton were damaged by lightning. Wind blew out several windows from a high rise apartment building in southeast Denver. Rainfall totaled 1.51 inches at Stapleton International Airport.
In 1997…torrential rain and damaging hail pummeled eastern sections of metro Denver. Hail up to 1.25 inches in diameter fell at the national weather service office on the site of the former Stapleton International Airport. The hail continued for about 15 minutes and accumulated to a depth of 2 to 3 inches…causing extensive damage to cars in the area. Heavy rainfall totaled 3.83 inches in about an hour from the nearly stationary thunderstorm. Numerous cars stalled along I-70…and several homes were flooded in east Denver. The roof of a building collapsed under the weight of the water. The next day several “fatalities” were discovered near the national weather service office; two prairie dogs were found dead along with three rabbits that either drowned or were killed by the large hail.
In 1999…lightning struck two residences in Littleton…but caused only minor damage. Lightning triggered a fire at a residence in cherry hills village. A small portion of the roof and ceiling were damaged before the fire could be extinguished.
In 2000…hail as large as 1.25 inches in diameter fell near Roggen northeast of Denver.
In 2004…heavy rainfall caused flooding on the Virginia Canyon Road near Idaho Springs…which had to be closed for repairs.
In 2006…the temperature climbed to a high of 100 degrees. The high temperature was not a record maximum for the date.
In 2007…a severe thunderstorm produced large hail…up to 1 inch in diameter…about 6 miles north of Northglenn.
June 21 to June 27 - This week in Denver weather history
A typical week during the spring and summer for Denver – tornadoes, hail, damaging winds and more.
19-21
In 1875…smoke from several large forest fires in the mountains was visible from the city on each of these days.
20-21 in 1897…high winds raked the city overnight. Southeast winds were sustained to 60 mph with gusts as high as 72 mph on the 20th. Southeast winds were sustained to 57 mph with gusts to 60 mph on the 21st.
In 2007…a brief hot spell produced two temperature records. The high temperature of 97 degrees was tied on the 20th. A new record high temperature of 99 degrees was established on the 21st.
21
In 1927…north winds were sustained to 40 mph with gusts to 44 mph.
In 1984…lightning struck and killed two children standing near a tree in a backyard in Lakewood. Strong thunderstorm downbursts caused a wind gust to 58 mph in Northglenn and knocked down two power poles near Brighton.
In 1988…lightning struck a home in Denver…causing about ten thousand dollars damage. Lightning damaged 3 homes in Littleton…and also hit a house in greenwood village that had been struck by lightning 7 years previously.
In 1991…thunderstorms produced widespread hail across metro Denver. Hail as large as 2 1/2 inches fell at several locations across southwest metro Denver. One storm spotter reported hail 8 inches deep near the intersection of I-25 and C-470. Heavy rain with the storms caused some street flooding. In Commerce City…several cars were under water… And in Westminster a police officer reported water up to the doors of his car. Damage to homes and automobiles totaled 55 million dollars.
In 1992…a tornado touched down briefly near Bennett. Another tornado was briefly on the ground near Strasburg.
In 1994…heavy thunderstorm rains caused flooding in metro Denver. Several vehicles were stalled in the high water on I-25. Lightning struck an underground natural gas line in Aurora…causing a fire. Widespread power outages were also observed.
In 1996…three homes were struck by lightning in Parker. The lightning struck the garage of the first home…which started a small fire that burned some siding and spread into the attic. A second home sustained damage to the attic when a small fire was started. The third home received only minor damage. Lightning also sparked two small grass fires in the area. A man in Lakewood received minor injuries when he was struck by lightning while working on a ladder. A funnel cloud was sighted in Castle Rock. Strong thunderstorm winds downed a large tree near crossroads mall in Boulder. A small tornado (f0) briefly touched down near Lafayette. No damage was reported.
In 1997…one inch diameter hail was measured in Boulder.
In 2002…a thunderstorm wind gust to 62 mph was recorded at Denver International Airport.
In 2005…severe thunderstorms produced hail to 1 inch in diameter in Broomfield along with 3/4 inch hail near Arvada.
In 2006…a man riding a motorcycle was struck and killed by lightning on U.S. Highway 36 between church ranch Blvd. And Sheridan Blvd. In Westminster. After the biker was struck…he and his motorcycle crashed into the center concrete median of the highway. The lightning bolt left a crater in the highway asphalt that measured 18 inches long…8 inches wide and 4 inches deep.
June 7 to June 13 - This week in Denver weather history
An extremely eventful week in weather history showing just how varied conditions can be. We of course see typical spring weather like tornadoes and hail but also a touch of snow and this week also marks the anniversary of the start of the Hayman Fire.
2-7
In 1921…heavy rainfall for nearly a week…on top of streams already swollen by mountain snowmelt…produced widespread flooding over the South Platte River basin…including the tributaries through the canyons to the west and southwest of Denver. Heavy rainfall over the 6-day period totaled 3.36 inches in Boulder…4.98 inches in Morrison…4.27 inches in Castle Rock…and 2.94 inches in the city of Denver. Rainfall amounts in the foothills were estimated between 3 and 6 inches. The narrow-gage tracks of the Colorado and southern railroad were destroyed in the Platte Canyon. From the mouth of the canyon through the city to near Brighton… The river spread from 1/2 to nearly 1 1/2 miles wide… Flooding farm and pasture land and destroying or damaging many bridges. In the city…many businesses along with as many as 500 homes were inundated…forcing their evacuation. Bridges were swept away. The high waters flooded the rail yards and stock yards in lower downtown…closing three adjacent packing houses. The heavy rains also caused flooding on Boulder creek in Boulder on the 6th.
6-7 in 2004…a brief hot spell produced 3 temperature records. High temperatures of 95 degrees on the 6th and 98 degrees on the 7th were record maximum temperatures for the dates. Low temperature of 68 degrees on the 7th was a record high minimum for the date.
In 2007…an unusually strong storm system brought very strong winds to the Front Range foothills and urban corridor. Peak gusts included: 92 mph at Boulder…85 mph…2 miles southwest of Boulder…83 mph…10 miles south of Boulder and 55 mph at Denver International Airport. High winds forced the closure of Mt. Evans Road and Trail Ridge Road. Several trees were uprooted across the urban corridor. In Aurora… The driver of a car was injured when some building material blew off the Fitzsimmons complex. The debris landed on the car and knocked the driver unconcious. The wind forced the cancellation of 60 flights at Denver International Airport. Xcel reported outages in Boulder…Denver…Lakewood and Longmont.
7
In 1904…a thunderstorm produced south winds to 40 mph with gusts to 50 mph…but only a trace of rain.
In 1942…heavy thunderstorm rainfall in south Denver caused flooding of shops…stalled motorists…and halted tramway service temporarily. Lightning damaged houses…but there was no loss of life. Precipitation totaled 0.53 inch in downtown Denver.
May 31 to June 6 - This week in Denver weather history
An extremely eventful week in Denver weather history. Most notably for longtime Thornton and Northglenn residents is the 28 year anniversary of the infamous Thornton Tornado which struck on June 3, 1981.
26-31
In 1995…a cool period with light morning showers and moderate to heavy afternoon showers and thunderstorms pushed rivers already swollen from mountain snow melt over their banks causing minor flooding. Streams and rivers such as the South Platte and Boulder creek flooded meadowlands…bike paths…roads near streams…and other low lying areas. No significant property damage was reported and crop damage was unknown. Rainfall totaled 1.79 inches at the site of the former Stapleton International Airport and only 1.51 inches at Denver International Airport.
29-1
In 1894…heavy rain combined with snowmelt runoff caused widespread flooding over the South Platte River basin. Rainfall was heaviest in the foothills where 5 to 8 inches were measured over the 4 days. Heavy rainfall west of Boulder flooded mining towns and damaged mining properties. In the canyons above Boulder…railroads and roads were washed out along with many bridges. The floodwaters spread into central Boulder and covered a wide area from university hill north to near Mapleton Hill to a maximum depth of 8 feet. Many houses were swept away…and every bridge in Boulder was destroyed. A few people…trapped in their homes by the floodwaters… Had to be rescued. However…the gradual rise of the flood waters resulted in only one death. Boulder creek spread to a width of nearly one mile in the pasture land to the east of Boulder. Extensive flooding on left hand creek north of Boulder washed away railroad and wagon bridges. The heavy cloudbursts caused flooding on bear creek…which washed away bridges…railroad tracks…and structures and destroyed the canyon roadway. Morrison sustained the heaviest flood damage on bear creek. In Denver…rainfall totaled only 1.50 inches on the 30th and 31st…but the heavy rainfall on upstream tributaries of the South Platte River caused the river to rise as much as 10 feet above the low water mark in the city…which caused some flooding of pasture land downstream to a depth of 6 feet near Brighton.
30-31
In 1935…heavy thunderstorm rains overnight caused flash flooding east of the city on both Kiowa and Bijou Creeks… Resulting in a total of 9 deaths. Most of the damage was on Kiowa Creek where there were more structures. The water rose rapidly during the storm…ripping houses and stores from their foundations and sweeping them downstream. Precipitation in Denver totaled only 0.01 inch. Hail fell in the city for a short time. The hail was very small and caused no damage.
In 1983…a late storm of rain and snow hit the Front Range. Over an inch of rain fell at some spots…and above 7 thousand feet…1 to 5 inches of snow whitened the ground. Some snow flakes even fell in the western suburbs of metro Denver on the night of the 30th.
In 2002…unseasonably warm weather at the end of the month resulted in 3 temperature records. High temperature of 91 degrees on the 30th equaled the record maximum for the date. Low temperature of 61 degrees on the 31st was a record high minimum for the date. High temperature of 93 degrees on the 31st was a record maximum for the date.
31 in 1917…rainfall totaled 0.55 inch and was mixed briefly with snow around midday. Only a trace of snow fell. Cold temperatures during the day resulted in a high of 44 degrees and a low of 35 degrees. The month closed as the coldest May on record with a mean temperature of only 48.7 degrees…about 8 degrees below normal. The cold temperatures during the month had a marked effect on shade trees and shrubs in the city. Elms were just starting to leaf. Leaves on cottonwoods and maples were only half formed. Lilacs were just blooming…and snowball clusters would not bloom for days.
In 1959…the public reported a tornado briefly touching the ground 10 miles south of Stapleton Airport. No damage was reported.
In 1984…a thunderstorm microburst produced a wind gust to 67 mph…7 miles east of Boulder.
In 1991…hail to golf ball size pummeled southern and southeastern sections of metro Denver and continued on east to Watkins. Several houses and cars were damaged. Later… Thunderstorms dumped heavy rain across the city of Denver… Causing street flooding in an area just south of downtown and just northwest of downtown. Water was up to 10 inches deep over northwest Denver. A brief tornado touched down in Castle Rock where 3/4 inch diameter hail also fell.
In 1993…thunderstorms dropped dime size hail in Commerce City.
In 1994…lightning struck an apartment in Louisville and damaged electronic equipment…including a computer.
In 2006…a severe thunderstorm produced 1 inch diameter hail near Boulder.
