Weather on September 21
Denver, CO
55 Years of Data
Avg High
77°F
Avg Low
44°F
Warmest
2022
76°F avg
Coldest
1995
37°F avg
About This Date
September 21st in Denver, CO typically brings pleasant fall weather, with average highs around 77°F and lows near 44°F — a 33°F daily swing. Over 55 years of records, the warmest September 21st was in 2022 (76°F average), while the coldest was 1995 (37°F) — a 39°F range across recorded history. Precipitation has occurred on 24% of recorded September 21st dates, with snow falling 4% of the time (heaviest snowfall: 1.6"). The last decade has been 6.8°F warmer on this date compared to 20-30 years ago.
The last decade has been 6.8°F warmer on this date compared to 20-30 years ago.
Planning for September 21st in Denver, CO? Great weather for outdoor activities.
Warming Trend
2.7°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 85° | 48° | 66° | — | — |
| 2024 | 91° | 49° | 70° | — | — |
| 2023 | 85° | 48° | 66° | — | — |
| 2022warmest | 96° | 55° | 76° | — | — |
| 2021 | 70° | 40° | 55° | 1.02" | — |
| 2020 | 87° | 49° | 68° | — | — |
| 2019 | 87° | 47° | 67° | — | — |
| 2018 | 85° | 50° | 67° | — | — |
| 2017 | 80° | 44° | 62° | — | — |
| 2016 | 88° | 61° | 74° | — | — |
| 2015 | 84° | 44° | 64° | — | — |
| 2014 | 81° | 56° | 68° | — | — |
| 2013 | 73° | 46° | 60° | — | — |
| 2012 | 82° | 44° | 63° | — | — |
| 2011 | 70° | 40° | 55° | 0.2" | — |
| 2010 | 94° | 50° | 72° | — | — |
| 2009 | 91° | 44° | 68° | — | — |
| 2008 | 82° | 48° | 65° | — | — |
| 2007 | 92° | 53° | 72° | — | — |
| 2006 | 78° | 42° | 60° | 0.56" | — |
| 2005 | 90° | 56° | 73° | — | — |
| 2004 | 85° | 43° | 64° | 0.74" | — |
| 2003 | 81° | 40° | 60° | — | — |
| 2002 | 84° | 41° | 63° | — | — |
| 2001 | 91° | 46° | 69° | — | — |
| 2000 | 77° | 40° | 58° | 0.36" | — |
| 1999 | 74° | 38° | 56° | — | — |
| 1998 | 54° | 45° | 49° | 0.08" | — |
| 1997 | 56° | 46° | 51° | 0.05" | — |
| 1996 | 78° | 43° | 60° | — | — |
| 1995coldest | 46° | 28° | 37° | 0.1" | — |
| 1994 | 64° | 32° | 48° | 0.76" | 0.1" |
| 1993 | 84° | 43° | 63° | — | — |
| 1992 | 75° | 50° | 63° | — | — |
| 1991 | 86° | 45° | 65° | — | — |
| 1990 | 69° | 48° | 59° | — | — |
| 1989 | 65° | 43° | 54° | — | — |
| 1988 | 74° | 52° | 63° | — | — |
| 1987 | 68° | 38° | 53° | — | — |
| 1986 | 70° | 43° | 56° | 0.3" | — |
| 1985 | 74° | 41° | 57° | — | — |
| 1984 | 81° | 53° | 67° | — | — |
| 1983 | 69° | 25° | 47° | — | — |
| 1982 | 78° | 45° | 61° | — | — |
| 1981 | 86° | 49° | 67° | — | — |
| 1980 | 79° | 47° | 63° | — | — |
| 1979 | 75° | 45° | 60° | 0.23" | — |
| 1978 | 69° | 26° | 48° | — | — |
| 1977 | 83° | 44° | 63° | — | — |
| 1976 | 74° | 44° | 59° | — | — |
| 1975 | 63° | 31° | 47° | — | — |
| 1974 | 67° | 42° | 54° | 0.05" | — |
| 1973 | 75° | 47° | 61° | — | — |
| 1972 | 75° | 44° | 60° | — | — |
| 1971 | 42° | 33° | 38° | 1.02" | 1.6" |
55 years of data from NORTHGLENN