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.
In 1896…a heavy thunderstorm produced sustained northwest winds to 45 mph with gusts to 50 mph and 1.02 inches of rain.
In 1965…a cloudburst dumped 1.99 inches of rain in 30 minutes at Stapleton International Airport. The storm was accompanied by strong winds gusting to 70 mph. The heavy rain flooded numerous streets in east Denver and Aurora. One inch diameter hail accompanied a cloudburst…9 miles southwest of Denver. A funnel cloud was sighted 25 miles northwest of Denver. In Aurora…there were unofficial reports of 2.30 inches of rain in 40 minutes and 3.30 inches of rain in 30 to 40 minutes. Rainfall totaled 2.05 inches at Stapleton International Airport. Rainfall of 2.42 inches for 24 hours on the 24th and 25th was the second greatest on record for July.
In 1977…a tornado touched down briefly in Aurora southeast of Cheery Creek Reservoir. No damage was reported. A funnel cloud was sighted for 4 minutes by national weather service personnel 10 miles north of Stapleton International Airport near Henderson.
In 1991…heavy rain…up to half an inch in 10 minutes…caused flooding in Westminster…Northglenn…and north Denver where a section of railroad track was washed away. At Stapleton International Airport…heavy thunderstorm rain totaled 1.85 inches and briefly reduced the visibility to 1/4 mile. Hail to 1/8 inch in diameter was also measured. A tornado touched down briefly near Fort Lupton. No damage was reported.
In 1998…heavy monsoonal thunderstorm rains caused flooding and flash flooding in eastern and southern sections of metro Denver…including Englewood and Aurora…when about 2 to 3 inches of rain inundated the area. Both I-25 and I-70 were closed for 2 to 3 hours as several low lying areas became impassable due to the high waters. The water was estimated to be 15 feet deep in one flooded underpass along I-25. As a result…the freeway was closed from south of 6th avenue to university blvd. Standing water forced the closure of I-70 at gun club road east of Denver. In Englewood…U.S. Highway 285 was closed…when high water made it impassable. Several cars were reportedly floating down the roadway near Sheridan Blvd. In Aurora…the intersection at Yale Ave. And chambers rd. Was flooded by high water up to 4 feet deep when a spillway on the high line canal was breached. Lightning also knocked out 11 transformers across metro Denver…causing several small fires and scattered power outages. Flood and flash flooding also occurred north of Strasburg when as much as 2.51 inches of rain fell in an hour. The deluge resulted in considerable flooding of local streets and County roads. Torrential rainfall of 2 to 3 inches in less than an hour triggered a flash flood in Virginia Canyon. County Road 279 between Idaho Springs and Central City was closed for two days to clear debris from mudslides. Several cars in Idaho Springs were washed off the road…and numerous basements were flooded in town. Thunderstorm rainfall totaled 2.69 inches at Denver International Airport.
In 2001…lightning struck two homes in Lafayette…damaging the roof and attic of one and shorting out the electrical system in another. Hail to 1 3/4 inch in diameter was measured 7 miles north of Castle Rock with 3/4 inch hail 7 miles north of Sedalia.
In 2005…heavy thunderstorm rain in the vicinity of the overland wildfire burn scar triggered a mudslide in Jamestown. Rocks the size of bowling balls…along with silt and mud slid down the mountain into the town. No one was injured. One parked car was buried by the debris.
In 2006…heavy thunderstorm rainfall caused flash flooding 1 mile north of the town of Westcreek in southwestern Douglas County. Several maintenance roads were washed out by the floodwaters.
Continue reading July 25 to July 31: This week in Denver weather history