August is here, and that means the downward slope of daily temperature begins. But the monsoon season remains in full force — at least for the first half of the month.
While the thermostat may start to creep toward cooler temperatures in August, the heat isn’t going anywhere fast. Denver's monthly mean temperature for August is 72.5 degrees (1981-2010 averages) and is the city’s second warmest month of the year.
The warmest temperature ever recorded during the month was 105 degrees on Aug. 8, 1878, according to the National Weather Service. The coldest temperature ever recorded in Denver for August was 40 degrees and occurred four times — Aug. 22, 1904, and on the 24th, 25th and 26th of 1910.
The main weather threats shift a bit away from tornadoes and the larger hail to mostly lightning and heavy rain, with the potential for some local flooding from some of the slower-moving storms due to a slightly weaker jet stream.
El Niño this year changed our weather pattern, taking the jet stream farther north and cutting off the monsoon flow. But the extended forecast is not that favorable for a strong southwest monsoon this year, at the expense of getting more of those storms pushing off to the north and east.
Rainfall totals from strong, rain-dumping thunderstorms are still the measure of interest. The mean monthly rainfall for the month is 1.62 inches. There is an average of nine days of measurable rainfall in August, according to the NWS. The wettest August occurred in 1979 when 5.85 inches of rain fell that month.
Mike Nelson has your August weather outlook in the video below:
Tornado season
Colorado entered tornado season in May, and the threat continues into August. Ninety percent of Colorado tornadoes occur during this four-month period, but tornadoes have been reported as early as February and as late as November.
There have been more than 2,000 tornado events recorded in Colorado and at least five deaths related to twisters since 1950.
The most tornado-prone county in Colorado — and the entire country — is Weld County, which has seen 268 tornadoes since 1950. The city and county of Denver has seen 16 tornadoes in the same period.
The biggest tornado event that struck Denver was on June 15, 1988. Seven people were injured when an F-3 tornado touched down in the southern part of the city, cutting an erratic path 2.5 miles long. The storm damaged 85 buildings and several cars and uprooted trees.
The injuries were minor, but according to NWS reports, very traumatic for some of those involved. A golfer was thrown 40 feet but was not hurt. A man clinging to a telephone pole was unscathed but lost both of his shoes. A woman holding a baby was sucked through a broken window of a convenience store, but neither the woman nor the baby was hurt.
Tornadic activity doesn't always occur in the usual places in Colorado. Although extremely rare, tornadoes and funnel clouds have been spotted on the Western Slope and in high-altitude areas. There have been three tornado touchdowns in Park County, occurring on June 8, 2014, Aug. 18, 2009, and Aug. 23, 2008. In 2011, a tornado was documented on Mount Evans with an elevation of 11,900 feet. And on June 20, 1975, an F-2 tornado touched down in Pitkin County.
On June 30, 2023, a funnel cloud was spotted east of Hartsel in South Park on Friday morning, according to the National Weather Service. The funnel cloud was reported near Wilkerson Pass and Elevenmile Canyon Reservoir and was moving northeast at about 30 mph, according to NWS.
