DENVER — A very hot summer in Colorado is now over... at least when it comes to weather data.
Meteorologists don't use the Autumnal Equinox to mark the beginning of fall because that date can vary from year to year. This year, astronomical fall will be on Sep. 22.
To ensure that seasonal weather comparisons remain fair, summer weather data is always recorded from Jun. 1 to Aug. 31.
The final numbers for summer 2021 show that it was a very hot three months for much of the western U.S. with at least one location in every western state having the hottest summer on record, except for New Mexico.
A temperature analysis done by Climate Central, Using only official weather reporting stations with a well established climate record of about 50 years, shows that three climate stations in Colorado had the hottest summers of all-time.
- Yampa in Routt County - Avg. temperature of 63.3 degrees
- Hayden in Routt County - Avg. temperature of 69.1 degrees (Inconsistent reporting in 2012 eliminated that year from contention. Otherwise that would have likely been warmer than 2021)
- Altenbern, an area in Garfield County north of De Beque - Avg. temperature of 71.2 degrees.
Steamboat Springs in Routt County just missed tying the hottest summer on record with an averge temperature of 63.8 degrees.
Castle Rock did not make the list due to a temperature reporting gap at that climate station in 1985, but with that flaw aside, 2021 was the hottest summer on record there with an average temperature of 75.4 degrees.
On the Front Range, several locations made the top 5 hottest summers of all-time including Denver’s official climate station at Denver International Airport.
The heat this summer came in waves. Denver had a 90-degree heat streak in July that lasted 8 days.
On average, heat streaks in Denver have doubled in length since 1970, from 6 to 12 days.
In June, it hit 100 degrees three days in a row. All three of those days were records, to go along with five other daily heat records set in Denver this summer. That is counting two high minimum temperatures in June.
For the whole year, nine daily high/low temperature records were tied or broken and only one cold record was broken back in February.
That makes 89% of the city’s temperature records in 2021 heat records. On average, heat records are getting broken more often over the past 50 years while cold records are become less common.
The most extreme heat this summer was focused on the western slope. Grand Junction even recorded its all-time hottest temperature of 107 degrees back on July 9.
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