Weather on December 21
Boulder, CO
55 Years of Data
Avg High
47°F
Avg Low
22°F
Warmest
1982
52°F avg
Coldest
1990
-14°F avg
About This Date
December 21st in Boulder, CO typically brings chilly winter weather, with average highs around 47°F and lows near 22°F — a 25°F daily swing. Over 55 years of records, the warmest December 21st was in 1982 (52°F average), while the coldest was 1990 (-14°F) — a 66°F range across recorded history. Precipitation has occurred on 15% of recorded December 21st dates, with snow falling 15% of the time (heaviest snowfall: 10.3"). The last decade has been 11.8°F warmer on this date compared to 20-30 years ago.
The last decade has been 11.8°F warmer on this date compared to 20-30 years ago.
Planning for December 21st in Boulder, CO? Bring layers as temperatures can vary throughout the day.
Warming Trend
0.7°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 61° | 32° | 46° | — | — |
| 2024 | 63° | 34° | 48° | — | — |
| 2023 | 61° | 36° | 48° | — | — |
| 2022 | 46° | -6° | 20° | 0.91" | — |
| 2021 | 63° | 28° | 46° | — | — |
| 2020 | 57° | 36° | 46° | — | — |
| 2019 | 59° | 28° | 44° | — | — |
| 2018 | 61° | 28° | 45° | — | — |
| 2017 | 53° | 17° | 35° | 0.56" | 3.5" |
| 2016 | 57° | 33° | 45° | — | — |
| 2015 | 48° | 27° | 37° | — | — |
| 2014 | 53° | 29° | 41° | — | — |
| 2013 | 31° | 12° | 21° | — | — |
| 2012 | 55° | 23° | 39° | — | — |
| 2011 | 39° | 22° | 30° | — | — |
| 2010 | 44° | 25° | 34° | — | — |
| 2009 | 57° | 27° | 42° | — | — |
| 2008 | 23° | 3° | 13° | — | — |
| 2007 | 47° | 26° | 36° | 0.18" | 1.4" |
| 2006 | 39° | 24° | 32° | 1.45" | 10.3" |
| 2005 | 62° | 33° | 48° | — | — |
| 2004 | 35° | 19° | 27° | — | — |
| 2003 | 58° | 32° | 45° | — | — |
| 2002 | 42° | 20° | 31° | — | — |
| 2001 | 49° | 20° | 34° | — | — |
| 2000 | 28° | 5° | 17° | — | — |
| 1999 | 34° | 24° | 29° | 0.53" | 1" |
| 1998 | 9° | -7° | 1° | 0.69" | 2.8" |
| 1997 | 46° | 18° | 32° | — | — |
| 1996 | 47° | 36° | 41° | — | — |
| 1995 | 33° | 16° | 24° | — | 0.1" |
| 1994 | 63° | 29° | 46° | — | — |
| 1993 | 39° | 19° | 29° | 0.28" | 1.4" |
| 1992 | 43° | 24° | 33° | — | — |
| 1991 | 50° | 21° | 36° | — | — |
| 1990coldest | -8° | -20° | -14° | 0.13" | 0.6" |
| 1989 | 46° | -7° | 20° | — | — |
| 1988 | 44° | 20° | 32° | — | — |
| 1987 | 44° | 16° | 30° | — | — |
| 1986 | 44° | 22° | 33° | — | — |
| 1985 | 64° | 29° | 46° | — | — |
| 1984 | 42° | 23° | 33° | — | — |
| 1983 | -2° | -15° | -8° | — | — |
| 1982warmest | 66° | 37° | 52° | — | — |
| 1981 | 54° | 38° | 46° | — | — |
| 1980 | 56° | 25° | 40° | — | — |
| 1979 | 57° | 30° | 44° | — | — |
| 1978 | 37° | 22° | 29° | — | — |
| 1977 | 50° | 20° | 35° | — | — |
| 1976 | 56° | 18° | 37° | — | — |
| 1975 | 49° | 25° | 37° | — | — |
| 1974 | 56° | 40° | 48° | — | — |
| 1973 | 59° | 33° | 46° | — | — |
| 1972 | 54° | 30° | 42° | — | — |
| 1971 | 55° | 30° | 43° | — | — |
55 years of data from BOULDER MUNI AP