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 →

Late June weather is usually relatively calm but when it turns severe, it can do so in spades.  Hail, flooding rains, tornadoes and more are not unusual.  This week in Denver weather history we see plenty of each of those including a hail storm in 1993 that damaged dozens of planes at Denver International Airport. 

19-21

In 1875…smoke from several large forest fires in the mountains was visible from the city on each of these days.

20

In 1888…northwest winds were sustained to 44 mph.
 
In 1956…a microburst caused a brief wind gust to 58 mph at Stapleton Airport.
 
In 1964…hail up to 1 inch in diameter was reported 1 mile north of Stapleton International Airport.  A 3 minute hail storm at both Stapleton International Airport and Lowry Field piled small hail to one half inch deep.
 
In 1967…a strong thunderstorm dumped 1.95 inches of rain in less than an hour at Stapleton International Airport and produced a wind gust to 54 mph.  The storm caused some flooding in east Denver and Aurora.  There was widespread flooding to streets…basements…and store buildings and automobiles.  Hail stones to 3/4 inch in diameter were measured at Buckley Field in Aurora.  A tornado touched down just south of Littleton…damaging a barn and killing several head of cattle.
 
In 1985…a wind gust to 61 mph was reported at Golden Gate Canyon in the foothills west of Denver.
 
In 1986…a man was killed by lightning at Highlands Ranch south of Denver.
 
In 1987…several tornadoes were sighted across metro Denver.  A tornado touched down briefly 5 miles west of Parker.  A tornado was sighted just north of Chatfield Reservoir.  A tornado just northwest of Watkins was on the ground for 15 minutes.  A tornado near Barr Lake was taped by a television news crew.  It had a double vortex and was on the ground for about 10 minutes.  In addition to the 4 tornadoes…severe thunderstorms dumped large hail across metro Denver.  One inch hail was reported in southeast Aurora; 3/4 inch hail fell at the Denver technology center…Buckley Field…and Franktown.
 
In 1992…several short-lived tornadoes occurred in the vicinity of Barr Lake.  No injuries or damages were reported.  A water spout was sighted over the southern end of Barr Lake.  Funnel clouds were also sighted on the grounds of the rocky mountain arsenal by national weather service observers at Stapleton International Airport.
 
In 1994…hail up to dime size covered I-25 south of Denver and near Sedalia.  Heavy rain caused local flooding on the interstate highway.
 
In 1996…strong thunderstorm winds downed several large tree limbs in Boulder on the University of Colorado campus.  A stop light in the city was also blown down.
 
In 1999…lightning sparked an oil tank fire near Brighton.
 
In 2001…large hail driven by strong thunderstorm winds raked Denver international and Front Range airports.  Wind gusting to 54 mph along with hail as large 2 inches in diameter punched at least 14 thousand holes and cracks in the flat roofs of several buildings at Denver International Airport. In addition…93 planes and hundreds of cars were damaged. About 100 flights had to be cancelled…stranding 1500 travelers.  The airport was completely shut down for about 20 minutes.  The storm also damaged a ground avoidance radar used to track planes on the ground to prevent collisions. Damage was estimated at 10 million dollars…not counting the damage to the 93 airliners.  The storm moved south and struck Watkins with hail as large as 2 1/2 inches in diameter and winds gusting to 60 mph.  A least 30 private planes at Front Range airport were destroyed.  The radome protecting the national weather service doppler radar…which was tracking the storm…also sustained damage.  The large hail…damaging winds…and heavy rain pummeled a mobile home park near Watkins.  In the park…52 mobile homes…14 recreational vehicles…3 homes…and a commercial building were damaged.  Siding was riddled with holes and windows were broken.  Vehicles sustained extensive damage and car windows were shattered.  A handful of people were treated for minor cuts and bruises.  The strong winds also flipped a tractor trailer along I-70 near Watkins.  The storm caused power outages…which affected about 1200 residents. Excluding the damage at Denver International Airport…damage estimates totaled 49 million dollars…making the storm the costliest in the last 3 years and the 10th costliest since 1984.  A small tornado touched down just east of Brighton… But did no damage.  Hail as large as 2 inches in diameter fell near Fort Lupton with 3/4 inch hail measured in Bennett.  Precipitation from the storm totaled only 0.23 inch at Denver International Airport.
 
Continue reading June 20 to June 26 – This week in Denver weather history →