Normally September is a relatively quiet month however we do occasionally see some extraordinary conditions. Our look back at this week in Denver weather history shows the earliest seasonal snowfall in Denver history, damaging lightning and the destruction of the Fourmile Canyon wildfire.
From the National Weather Service:
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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.
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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.
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In 1938…heavy cloudbursts in the foothills near the top of Genesee Mountain caused flash flooding on Bear Creek at Morrison. Nearly 8 inches of rain fell just north of Morrison in 6 hours and drowned 6 people in a car between Morrison and Kittredge. Damage was estimated at nearly a half million dollars. Flash flooding also occurred on south Boulder Creek in Eldorado Springs. Rainfall totaled 4.42 inches in Eldorado Springs…and rainfall was estimated to more than 6 inches in the foothills west of the town. Many buildings and residences were damaged in Eldorado Springs…and bridges were swept away. The high waters forced residents from their homes as far downstream as Erie. This was the flood of record on South Boulder Creek.
In 1973…hail to 3/4 inch diameter was reported in Boulder.
In 1987…lightning struck two men who were standing under a tree in downtown Denver. Both were seriously injured and hospitalized.
In 1996…lightning sparked a brush fire in the south buffer zone of the Rocky Flats Environmental Test Facility. No structures were damaged…but the fire burned about 100 acres of grassland before being contained.
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In 1892…there was a trace of rainfall each day. This… Together with a trace of rain on both the 7th and 8th…was the only rainfall of the month…making the month the driest on record. The monthly record was equaled in 1944.
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In 1901…a thunderstorm produced rain…hail of unknown size… And south winds sustained to 40 mph with gusts to 43 mph.
In 1961…Labor Day snow storm is the earliest date of the first snow…trace and measurable…of the season. The heavy wet snow broke many limbs from trees that were still in full foliage. The storm produced 4.2 inches of snowfall at Stapleton Airport with nearly a foot of snow in western suburbs and in the foothills. Minimum temperature of 33 degrees was a record for the date and the coldest ever recorded so early in the season.
In 1999…severe thunderstorms dumped large hail across metro Denver. Hail as large as 1 inch in diameter was measured near Cherry Creek in Aurora and near Bennett. Hail to 3/4 inch in diameter fell in the city of Denver.
In 2002…a thunderstorm produced a wind gust to 51 mph at Denver International Airport.
In 2003…very heavy thunderstorm rain washed out parts of the Virginia Canyon Road above Idaho Springs. Up to 4 feet of mud reportedly washed down the road during the storm. Several vehicles were trapped on the road. In Idaho Springs…several streets…including the main street… Were also buried in mud and gravel. Some buildings in town experienced minor flooding…including the basement of the town library and the police station.
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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.
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In 1909…apparent post-frontal heavy rainfall totaled 1.94 inches in downtown Denver. North winds were sustained to 19 mph.
In 1944…a trace of rain fell. This together with a trace of rain on the 9th…10th…and 30th was the only precipitation for the month. The total of a trace of precipitation for the month equaled the driest September on record first set in 1892.
In 1960…the highest recorded temperature in September…97 degrees…occurred. The same temperature also occurred on September 5…1899…September 1…1995…and September 4… 1995.
In 1989…a strong thunderstorm wind gust flipped a plane taxiing on a private runway in Adams County east of Denver. Two people were slightly injured and the plane was heavily damaged.
In 1992…strong winds developed across metro Denver behind a pacific cold front. Sustained winds above 40 mph with gusts as high as 60 mph were recorded mainly in and near the foothills. Pre-frontal south winds gusted to 37 mph at Stapleton International Airport.
In 1995…two people were injured when lightning struck their home in Lakewood. The lightning entered the attic where it started a small fire. It then traveled through the walls… Exploding a mirror and spraying glass on the residents. Lightning also sparked small grass fires near Aurora…Denver International Airport…and Bennett. The highest recorded temperature in September…97 degrees…occurred. The same temperature also occurred on September 5…1899…September 4…1960…and September 1…1995.
In 2000…thunderstorm winds gusted to 64 mph in Castle Rock.
Continue reading September 2 to September 8: This week in Denver weather history