Denver Climatological Preview - August 2023

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Preview of Thornton's August Weather - The Winding Down of Summer

A Preview of Thornton's August Weather - The Winding Down of Summer As summer vacations wind down and families prepare to send their kids back to school in August, Colorado weather also starts to settle down. The chances for severe weather decrease markedly during August and by the end of the month daytime temperatures are dropping quite a bit as well.

The August overall average temperature of 72.5 degrees (1981 - 2010) makes it the second warmest month of the year behind July. At the start of the month Denver usually averages around 90 degrees for a high temperature. By the end of August that drops to 84 degrees.

Similarly, nighttime lows drop from 60 to 54 from the start to the end of the month. As the end of the month comes, we start to notice our daylight hours getting fewer and even can feel a bit of a nip in the early morning air.

Historical temperature extremes for August are somewhat interesting.

First, the highest temperature ever reached in Denver was actually recorded in August - 105 degrees on August 8, 1878 (also tied on July 20, 2005, June 25, 2012 and June 26, 2012).

Second, while there has never been snow in Denver in August, four times the mercury has dropped to 40 degrees to serve as a reminder the white stuff isn't too far off. Those chilly temperatures occurred on August 22, 1904 and August 24, 25 and 26, 1910.

Generally clear skies can be expected between midnight and noon but the afternoon often brings showers and thunderstorms. These storms typically develop over the foothills then bring precipitation to the Denver metro area. The slow movement of storms can produce heavy rain.

Despite that moisture, the chance for severe weather decreases considerably compared to the first two months of summer. Cooler air near the surface helps to create a stable atmosphere thus keeping thunderstorms from usually becoming too intense. After the middle of August, tornadoes and damaging hail are pretty rare.

Denver's August Extremes

August: Denver's Top 5 Warmest (mean temperatures):
77.0 degrees 2011
75.8 degrees 1937
75.4 degrees 2007
75.3 degrees 1995
75.0 degrees 1994, 2012

August: Denver's Top 5 Coldest (mean temperatures):
66.5 degrees 1915
66.6 degrees 1927
67.8 degrees 1920
67.9 degrees 1884
68.0 degrees 1888

August: Denver's Wettest
5.85 inches 1979
4.47 inches 1951
3.87 inches 1923
3.69 inches 1991
3.52 inches 1997

August: Denver's Driest
0.02 inches 1924
0.05 inches 1900, 1917
0.06 inches 1960
0.16 inches 1974
0.19 inches 1948

Outlook for August 2023

The long-range forecasts from the Climate Prediction Center do not indicate any significant drivers for out of the ordinary temperatures but do indicate it could be a wet one. The agency gives the vast majority of the state equal chances of seeing above, below or near average temperatures. In terms of precipitation, however, all but the southwestern corner of Colorado are given an above average probability of seeing above normal levels of precipitation.

For More Information

Temperature Normals and Extremes for August

Monthly Temperature, Rainfall and Snowfall Extremes for August

AUGUST AVERAGE STATISTICS *
Normals & Means, 1981 - 2010
 
TEMPERATURE
AVERAGE HIGH 87.2 (86.0)
AVERAGE LOW 57.9 (57.4)
MONTHLY MEAN 72.5 (71.7)
DAYS WITH HIGH 90 OR ABOVE 9
DAYS WITH HIGH 32 OR BELOW 0
DAYS WITH LOW 32 OR BELOW 0
DAYS WITH LOWS ZERO OR BELOW 0
   
PRECIPITATION
MONTHLY MEAN 1.69 INCHES (1.82 INCHES)
DAYS WITH MEASURABLE PRECIPITATION 9
AVERAGE SNOWFALL 0
DAYS WITH 1.0 INCH OR MORE SNOWFALL 0
   
MISCELLANEOUS AUGUST AVERAGES
HEATING DEGREE DAYS 10 (9)
COOLING DEGREES DAYS 244 (217)
WIND SPEED (MPH) 8.0 MPH
WIND DIRECTION SOUTH
DAYS WITH THUNDERSTORMS 8
DAYS WITH DENSE FOG 1
PERCENT OF SUNSHINE POSSIBLE 71
   
AUGUST EXTREMES
RECORD HIGH 105 ON 8/8/1878 (TIED AS HOTTEST DAY IN DENVER HISTORY)
RECORD LOW 40 ON 8/26/1910, 8/25/1910, 8/24/1910, 8/22/1910
WARMEST 76.8 IN 1937
COLDEST 66.5 IN 1915
WETTEST 5.85 INCHES IN 1979
MAXIMUM 24 HOUR MOISTURE 3.43 INCHES IN 1951
DRIEST 0.02 INCH IN 1924
SNOWIEST (Could include hail) NONE EVER RECORDED IN AUGUST
LEAST SNOWIEST NONE EVER RECORDED IN AUGUST

* Historical weather statistics gathered from the National Weather Service's Denver / Boulder forecast office data archives. Numbers in parentheses reflect "old" normals from 1971 to 2000 before recent updating by the NCDC.