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Public Information Statement
National Weather Service Denver/Boulder CO
259 AM MDT FRI SEP 5 2025

...Today in metro Denver weather history...

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.
1-30  In 2020...a worsening drought that started in the spring and
        continued through September. Outside of an early season
        snow on the 8th...the month of September was another
        unseasonably warm and dry period. The combination
        of hot...mostly dry conditions...and critically dry fuels...
        resulted in a continuation and rapid expansion of several
        massive wildfires. The Cameron Peak fire...which became the
        largest in the state`s history started on August 13th...and
        continued through September. As a result...very poor air
        quality continued to impact Denver and the entire Front
        Range.  Denver recorded the most days ever with a high
        temperature of 90 degrees or better; 75 days.  The last
        of which was 91 degrees on the 24th.  The previous
        record was 73 days set in 2012.
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.
5-8   In 2020...a strong upper level low brought an end to record
        heat to the Front Range urban corridor...and provided Denver
        its second earliest measurable snowfall on record. Numerous
        heat records were set leading up to the snowfall...and
        several new snowfall and cold records were also broken in
        this abrupt bout with winter.  Denver set its all time
        record high for September...reaching 101 degrees during the
        afternoon. This was also the latest date a 100 degree
        reading has ever been observed in Denver.  Another daily
        record high was then tied on September 6th when Denver hit
        97 degrees. September 7th was the last day of heat when
        Denver`s high temperature reached 93 degrees.  That tied
        Denver for the record for the number of 90 degree days for
        a year at 73...and was also the warmest temperature ever
        recorded before a day of measurable snowfall.  By the
        evening of September 7th...a series of cold fronts
        progressed southward from Wyoming into Colorado...
        dropping the temperature into the low 30s by the early
        morning hours of September 8th.  Snow developed across
        the Front Range mountains and foothills overnight...
        while a mix of rain and snow developed along the I-25
        corridor.  A few locations picked up light snowfall
        accumulations in the morning. Accumulating snow was
        mostly confined to the higher elevations much of the
        day...before spreading across the plains during the
        late afternoon and evening. Storm totals ranged from
        4 to 10 inches in the mountains...with 3 to 6 inches
        near the foothills.  A total of 5.6 inches of snow
        was measured at the NWS Boulder office...while at
        Denver International Airport...the official
        measurement was 1.0 inch.
5-9   In 1988...layers of smoke aloft from large forest fires in
        Yellowstone National Park completely obliterated the sun
        at times.  At Stapleton International Airport...surface
        visibility was reduced at times to 5 and 6 miles in smoke.
5-13  In 2010...the Fourmile Canyon Wildfire...northwest of Boulder...
        broke out on the morning of the 5th.  It originated from
        an unattended fire pit at a local residence. The wildfire
        quickly consumed 5 1/2 square miles or 3500 acres the
        first day...and forced the evacuation of over three
        thousand residents.  Erratic 45-mph gusts sent the fire in
        two directions at times. Very dry weather conditions
        preceded the fire. The combination of strong winds...low
        relative humidities and dry fuels allowed the wildfire
        spread rapidly through the steep...heavily forested terrain.
        The flames were reportedly 20 to 50 feet in length.  Towns
        within the burn area included Salina...Wallstreet and Gold
        Hill. The dry conditions coupled with gusty winds ranging
        from 45 to 64 mph persisted for several more days. Fire
        managers used as many as 700 firefighters and support
        personnel from 35 agencies and seven air tankers to battle
        the wildfire.  A total of 6181 square acres or
        approximately 10 square miles were burned.  The Fourmile
        Canyon Wildfire was the most destructive fire in Colorado
        history in terms of the damage to personal property.  It
        destroyed 171 homes with an estimated cost of 217 million
        dollars.

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