Normally one doesn’t associate tornadoes with September weather in Denver but they can and do happen as we see in our look back in Denver weather history for the week.  We have a couple of occasions of twisters and of a funnel cloud.  Other severe weather like hail, damaging wind and flooding rains have also occurred.   Oh, and should we mention the dreaded “S” word – snow?

11-12

In 1974…post-frontal rain changed to snow overnight for the first snow of the season.  Snowfall totaled only 1.8 inches at Stapleton International Airport where north winds gusted to 40 mph on the 11th.  High temperature of only 46 degrees on the 12th set a new record low maximum for the date.

12 

In 1887…west winds to 42 mph were recorded in the city.
 
In 1952…a thunderstorm outflow produced strong southeast winds gusting to 52 mph.  Surface visibility at Stapleton Airport was briefly reduced to 2 miles in blowing dust.
 
In 1963…a nearly stationary…white tornado near Bennett was sighted from Denver.  No damage was reported.
 
In 1989…an early snowfall and the first of the season brought 2 to 3 inches of slush to metro Denver.  More snow whitened the foothills west of Denver where 6 inches were measured at Evergreen.  The snow fell on leaf laden trees… And sagging branches onto power lines caused outages.  Much of Denver’s snow fell during the evening rush hour…creating traffic chaos.  Snowfall totaled 2.3 inches at Stapleton International Airport where the maximum snow depth on the ground was only 1 inch due to melting.
 
In 1994…thunderstorm microburst winds gusted to 67 mph in Boulder.  No damage was reported.
 
In 2002…a severe thunderstorm produced hail as large as 1 inch in diameter near Castle Rock.

Continue reading September 12 to September 18 – This week in Denver weather history →

September is typically one of our quietest weather months and in fact it is our sunniest.  That doesn’t however mean we can’t experience weather extremes.  This week in Denver weather history we see everything from scorching heat and severe thunderstorms to snow and damaging wind.  For more about September’s weather, check out our September weather preview.

1-5

In 1995…record breaking heat occurred on the first 5 days of the month when the temperature climbed into the 90’s on each day.  Record high temperatures of 97 degrees on both the 1st and 4th equaled the all-time record maximum for the month.  High temperature of 95 degrees on the 3rd was a record for the date.  High temperatures of 94 degrees on both the 2nd and the 5th were not records.  The low temperature of 64 degrees on the 4th equaled the record high minimum for the date.

1-7

In 1978…the temperature reached 90 degrees or more on seven consecutive days with the highest temperature…94 degrees… Recorded on both the 4th and 6th.

3-6

In 1909…rainfall for the 4 days accumulated to 3.97 inches in Boulder…while in Denver rainfall totaled 2.45 inches on the 4th…5th…and 6th.

5  

In 1899…the highest recorded temperature in September…97 degrees…occurred.  The same temperature was also reached on September 4…1960…and September 1 and 4…1995.
 
In 1940…a severe wind and hail storm confined mostly to the west and north parts of the city occurred shortly after 4:30 pm.  Hail stones ranged in size from 1/4 to 1/2 inch in diameter. In north Denver…hail piled to a depth of 4 inches.  Flooding occurred in one underpass…which stalled 2 cars.  One girl was injured when the weight of the hail flattened a porch on which she stood. Northeast winds were sustained to 29 mph with gusts to 32 mph in downtown Denver.
 
In 1987…a thunderstorm complex produced hail as large as 1 3/8 inches in diameter…2 miles east of Buckley Field in Aurora.  No damage was reported.

Continue reading September 5 to September 11 – This week in Denver weather history →

Certainly this time of year we start to see temperatures drop and the conditions moderate.  This is usually one of Denver’s most pleasant times of years when the heat of summer fades and the snow and cold of winter is still far away.  That however wasn’t the case when the most notable event in Denver weather history this week occurred.  It was in 1961 on the 3rd of September that Denver received its earliest measurable snowfall – 4.2 inches!

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.

29

In 1876…after the passage of a gentle rain shower to the east during the late evening hours…the moon shone brightly and a remarkably bright lunar rainbow appeared.

In 1910…an apparent cold front produced sustained northeast winds to 40 mph.

In 1946…the high temperature warmed to only 55 degrees…the record low maximum for the month.

In 1989…a spectacular lightning display knocked out power to 300 blocks in southeast Denver.  One bolt started a fire in a lumber yard in the northeast part of the city…and the attic of a home in the same area was set ablaze by a lightning bolt.

In 1996…3/4 inch diameter hail was measured in Parker.

In 2000…lightning struck two homes in Thornton.  The extent of damage was unknown.

In 2002…two small tornadoes caused damage in southeast metro Denver.  The first tornado…associated with a multi-vortex storm…touched down briefly near E-470 and South Jordan Road.  Some fences were damaged…and a few trees were blown down.  A few of the homes also sustained minor roof damage. Damage from this storm totaled 100 thousand dollars.  The second tornado associated with the storm touched down in a subdivision that was under construction at Gartrell and Arapahoe roads.  Four large condominiums under construction were destroyed.  The most heavily damaged portions of the structures were still in the framing stages.  Adjacent sections where enclosed walls were in place were not destroyed.  A man suffered 4 broken ribs and several cuts and bruises when the trailer he sought shelter in was flipped three times and torn apart by the twister.  Damage from this storm totaled 6 million dollars. A severe thunderstorm produced 1 inch diameter hail near Evergreen.

In 2006…severe thunderstorms produced large hail in the foothills west of Denver.  Hail to 1 inch in diameter fell near Blackhawk.  Hail as large as 7/8 inch was measured near Idaho Springs…along with 3/4 inch hail near Nederland and Conifer.

Continue reading August 29 to September 4 – This week in Denver weather history →

Lightning is a very real danger here in Colorado.  The outdoor-centric lifestyle we lead oftentimes puts us in situations when we are better off heading for cover.  The dangers of not properly taking shelter when lightning is in the area are highlighted by a number of events in our look back at this week in Denver weather history.

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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 

In 1898…an apparent thunderstorm produced southwest sustained winds to 40 mph with gusts to 43 mph.
 
In 1903…a late afternoon thunderstorm produced rain…hail… And east winds sustained to 40 mph with gusts to 44 mph.
 
In 1904…the lowest recorded temperature in August…40 degrees…occurred.  The same temperature also occurred on three consecutive days…August 24…25…and 26 in 1910.
 
In 1965…heavy rain and hail caused some damage from flooding over northern Douglas County from Castle Rock to Franktown.
 
In 1981…thunderstorms moved across metro Denver.  At least 5 funnel cloud sightings were reported.  Funnel clouds were seen at 96th Ave. And Sheridan Blvd. and at 92nd Ave. and Federal Blvd. In Westminster and 7 miles north of Stapleton International Airport.  Lightning injured two people in Boulder.  A quarter inch of rain fell in just 5 minutes in Brighton.  Up to 3/4 inch of rain doused Parker in 30 minutes.
 
In 1983…3/4 inch diameter hail was reported at Kittredge… Along with 0.60 inch of rain in 25 minutes.
 
In 1984…a thunderstorm dumped 4 inches of rain on Brighton in 90 minutes…causing extensive street flooding in the downtown area.
 
In 1987…over an inch of rain fell in 24 hours throughout most of metro Denver.  A public library suffered water damage to the ceiling…carpet…and a few books.  Rainfall was 0.76 inch at Stapleton International Airport.
 
In 1990…lightning knocked out power to about 2500 homes in Lakewood for about an hour.
 
In 1991…National Weather Service personnel at Stapleton International Airport sighted an apparent tornado briefly on the ground 3 miles west-northwest of the airport.  No damage was reported.
 
In 1995…lightning struck 3 electrical power substations in Louisville.  Residences of more than 4500 people were without power from 30 minutes to more than an hour.
 
In 1996…between 1 and 3 inches of rain fell across metro Denver.  As a result…several low lying areas were flooded. A bicyclist was swept into a fast moving creek when he tried to cross a flooded bike path.  The man was washed downstream about 15 feet before getting snagged by a tree stump.  He and a man who tried to rescue him received minor injuries.  The heavy rain caused numerous power outages…false fire alarms…and traffic accidents. In Lakewood…telephone service to around 60 thousand residents was knocked out when a switching center was flooded.  Funnel clouds were sighted near Chatfield Reservoir and Highlands Ranch.
 
In 2000…lightning sparked a blaze which gutted a 10-unit apartment building in Highlands Ranch.  Twenty-eight people were left homeless.  Damage was estimated at 2 million dollars.
 
In 2007…severe thunderstorms produced large hail…up to 1 1/4 inches in diameter…in the vicinities of Castle Rock… Elizabeth and Franktown.

Continue reading August 22 to August 28 – This week in Denver weather history →

While not as common this time of year, severe weather can still strike as we close out summer.  Most notable are the heavy rain events that can come along as a result of the monsoon season.  The dangers of these are oftentimes ignored and as we see can oftentimes turn deadly.

15

In 1899…a thunderstorm produced southwest sustained winds to 43 mph with gusts to 46 mph.
 
In 1972…a pilot reported a funnel cloud briefly touching the ground in open fields…17 miles east-northeast of Stapleton International Airport.
 
In 1980…thunderstorm winds gusted to 55 mph in Boulder.
 
In 1982…brief heavy rain and winds estimated as high as 70 mph occurred in the conifer-Evergreen area.  No damage was reported.
 
In 1990…lightning triggered a small attic fire in a house near Sedalia…20 miles south of Denver.  A furious lightning storm caused widespread power outages across southern sections of metro Denver.  One lightning bolt knocked out an electrical substation…causing a 90-minute blackout in southeast Denver affecting nearly 10 thousand homes and businesses.
 
In 2007…severe thunderstorms produced large hail…up to 2 inches in diameter…near Larkspur.   Extensive damage to vehicles in the area was reported.  In Parker…lightning struck a residence.  The ensuing fire damaged the attic and top floor; causing $100000 in property damage.
 
In 2008…at least three homes were hit by lightning during the early morning hours in Arapahoe County.  Lightning also struck two homes in Castle Rock…damaging the roofs.

Continue reading August 15 to August 21 – This week in Denver weather history →

Monsoon season in Colorado typically brings short-lived but heavy rains.  These can result in flash flooding and we see that in our look back at this week in Denver weather history.  Also notable are the number of lightning deaths and injuries as well as hail events and even a swarm of grasshoppers!

8 

In 1874…swarms of grasshoppers invaded the city.  Millions of them were seen cruising through the air.  The insects were apparently picked up by a thunderstorm gust front and carried into the city.  The grasshoppers had ravaged crops in surrounding counties for the last month.
 
In 1878…the highest temperature ever recorded in Denver…105 degrees…occurred at 3:20 pm.  This temperature was equaled on July 20th in 2005.
 
In 1969…the temperature reached 100 degrees at Stapleton International Airport.
 
In 1976…in Thornton…a 13 year old boy riding a bicycle was struck and killed by lightning.
 
In 2000…lightning struck three homes in central Arapahoe County east of Denver.  Damage was estimated at 47 thousand dollars.
 
In 2003…hail to 1 inch in diameter pelted Denver.  Hail to 7/8 inch was measured in Boulder.
 
In 2008…heavy rain also caused flash flooding over south Denver and its nearby suburbs. Heavy rain…from 2.5 to 4 inches…fell in less than 90 minutes.  Firefighters rescued 20 people as the water quickly rose along creeks…flooded roadways…and stranded motorists.  Three people had to be rescued along Cherry Creek when the bike path flooded.  In Evergreen…a man suffered minor injuries when he was struck by lightning.  It entered his finger…traveled down his body… And exited his foot.

Continue reading August 8 to August 14 – This week in Denver weather history →

August isn’t normally associated with severe weather but our look back at the history books show it certainly can and does happen.  We see many occurrences of dangerous lightning and of particular note is the flood events – a byproduct of the monsoon season the first of August brings.

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.

1

In 1888…heavy rain in the mountains and foothills caused flooding on clear creek in Golden.  The high waters also washed away portions of the railroad tracks in the canyon between Idaho Springs and Golden.
 
In 1901…the temperature reached a high of 100 degrees in the city.
 
In 1902…the high temperature climbed to 100 degrees in downtown Denver.
 
In 1914…a thunderstorm produced 1.00 inch of rainfall in just 21 minutes and north winds sustained at 43 mph with gusts to 50 mph.  Rainfall totaled 1.17 inches.
 
In 1938…the temperature climbed to a high of 100 degrees in downtown Denver…which is the record maximum for the date.  The temperature was also recorded on this date in previous years.
 
In 1976…flight operations at Stapleton International Airport were suspended for 90 minutes when the airport tower radar was knocked out and water reached a foot deep on some taxi ramps after 1.50 inches of rain fell in one hour.  Heavy rain also caused minor flooding in east Denver and Aurora where lightning damaged the roof of a home and injured the owner.  One young man was swept down a flooded ditch…but was rescued by firemen.  A number of rafts were floated in flooded streets.  Thunderstorm rainfall totaled 1.71 inches at Stapleton International Airport.
 
In 1978…a tornado damaged a house and broke a power pole 5 miles northwest of Parker.  A microburst wind gust to 52 mph briefly reduced visibility to 1 mile in blowing dust at Stapleton International Airport.
 
In 1985…heavy thunderstorms roared through the southern and western sections of metro Denver…producing large hail and heavy rain.  Lightning hit a recreational vehicle trailer causing it to burn.  There was a lot of street flooding over western suburbs where rainfall totaled over 2 inches in some areas.  One inch diameter hail was reported in Littleton and near Evergreen.  Hail piled 4 to 6 inches deep at Tinytown in the foothills southwest of Denver.
 
In 1990…a small rope-like tornado was spotted in open country 15 miles southeast of centennial airport. No damage was reported from the twister.
 
In 1992…pilots reported a funnel cloud near the construction site of the new Denver International Airport.  A few minutes later…a tornado was reported near Bennett.  The tornado remained on the ground for about 18 minutes and was visible from the national weather service office at Stapleton International Airport.  Thunderstorm wind gusts to 70 mph were reported near Bennett and Watkins with a wind gust to 60 mph at Brighton.  Two men were injured when struck by lightning.  A young man sustained serious injuries when struck by lightning while jet skiing on Cheery Creek Reservoir.  A man received only minor injuries when struck by lightning while golfing in Westminster.
 
In 1994…heavy thunderstorm rains in the foothills west of Denver caused the closure of the Virginia Canyon Road north of Idaho Springs by rocks and debris.
 
In 2001…a 34 year old man on the South Platte River bike path in Denver received minor injuries when lightning struck a nearby tree.  Lightning…coupled with strong thunderstorm winds…knocked out electrical power to about 10 thousand homes and businesses in Golden.
 
In 2006…strong thunderstorms hit southern metro Denver. A severe thunderstorm wind gust estimated to 71 mph knocked down a tree in Aurora near Cherry Creek. Lightning sparked a fire in a home near Lone Tree and struck a transformer at an RTD light rail station at Interstate 25 and Yosemite street.  Heavy thunderstorm rainfall forced the closure of Arapahoe road between Holly and Quebec streets due to high water.  Flooding was also reported near park meadows mall and greenwood village.  Heavy rainfall also caused flooding in Highlands Ranch…Lone Tree…and Parker.  Water up to 6 inches deep was reportedly running over the roads.

Continue reading August 1 to August 7 – This week in Denver weather history →

Colorado’s unofficial severe weather season is during the months of May and June.  However, as we look back in Denver weather history, we see that July can oftentimes hold its own.  Many occurrences of flooding, scorching heat, and even tornadoes have been recorded.  Most notably, this week marks the 24th anniversary of the Big Thompson Flood – Colorado’s deadliest weather disaster ever.

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.

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.

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.
 
Continue reading July 25 to July 31 – This week in Denver weather history →

As we move further into summer, we see a decrease in traditional things associated with severe weather like tornadoes.  However, there is a corresponding increase in heavy rain as Colorado gets closer to its monsoon season.  We see many occurences of dangerous flooding as well as damaging hail, deadly lightning and more as we look back at this week in Denver weather history.

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.

6-23 

In 1901…a streak of 18 consecutive days of 90 degrees tied for second with another streak set in the summer of 1874. The record of 24 consecutive days was established in the summer of 2008.

7-25 

In 1934…a streak of 15 consecutive days of 90 degrees ranked 5th on the list of hot streaks.  The record of 24 consecutive days was established in the summer of 2008.

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.

Continue reading July 11 to July 17 – This week in Denver weather history →

Closing out June and entering July our look back at this week in Denver weather history is marked by severe weather and scorching heat.  Damaging hail to dangerous lightning are two common occurrences as is record-setting heat waves.

From the National Weather Service:

21-3 

In 2002…the maximum temperature in Denver equaled or exceeded 90 degrees for 13 consecutive days…equaling the 5th longest such streak on record.  The record of 18 consecutive days was set during the summer of 1901.

26-27

In 1965…wind gusts to 38 mph were recorded in downtown Boulder…causing widespread minor damage.  A microburst wind gust to 41 mph was recorded at Stapleton International Airport.

27

In 1873…Pikes Peak was hidden from view by smoke from forest fires in the mountains to the southwest of the city.
 
In 1927…the temperature cooled to a low of only 72 degrees… The all-time record high minimum for the month.
 
In 1980…lightning injured 4 people on a baseball diamond in Broomfield.  The bolt seriously injured the pitcher while also striking (out) the batter…catcher and second baseman.
 
In 1987…a microburst wind gust to 53 mph was recorded at Stapleton International Airport.
 
In 1990…the temperature reached a high of 102 degrees… Setting a new record maximum for the date.
 
In 1993…thunderstorm winds gusted to 60 mph across parts of metro Denver.  A wind gust to 50 mph blew over a 30-foot canvas tent at an amusement park southeast of Denver. Fifteen people…mostly children…were injured.  Microburst wind gusts to 33 mph were recorded at Stapleton International Airport.
 
In 2002…heavy rain…up to 3/4 inch…fell across sections of the Hayman burn area near Cheeseman Reservoir.  Several forest service roads were washed out and many culverts were plugged by debris.
 
In 2004…heavy rain producing thunderstorms caused rock and mud slides across the overland fire burn area in Jamestown. An estimated 50 tons of sand…dirt…rock…and ash slid into town…filling a culvert under main street.  The slide covered 150 to 225 feet of Main Street.  The flood was produced by half an inch of rain in 30 minutes.  A deluge of very heavy rainfall from nearly stationary thunderstorms caused flooding and flash flooding problems over parts of Jefferson and Douglas counties.  An automated rain gage in Golden measured 3.60 inches of rainfall in one hour.  Numerous homes were flooded in Golden…including one that was 146 years old. The home was listed as a complete loss.  State Highway 93 had to be closed from the Pine Ridge subdivision to the Golden Gate Canyon Road.   At the height of the storm…about 4 feet of water covered State Highway 93 through Golden… Forcing its temporary closure.  Several intersections were also flooded and impassable.  Rock and mud slides were reported in Golden Gate Canyon State Park.  At the Deer Creek Golf Course at Colorado 470 and Kipling…the greens were completely inundated by floodwaters.  Some backyards near the golf course were partially washed out.  In Douglas County…water up to a foot deep covered the roadways in Roxborough State Park.  The Waterton Canyon Road also had to be closed due to high water.

Continue reading June 27 to July 3 – This week in Denver weather history →