Weather on December 20
Longmont, CO
55 Years of Data
Avg High
44°F
Avg Low
16°F
Warmest
2025
52°F avg
Coldest
1990
2°F avg
About This Date
December 20th in Longmont, CO typically brings chilly winter weather, with average highs around 44°F and lows near 16°F — a 28°F daily swing. Over 55 years of records, the warmest December 20th was in 2025 (52°F average), while the coldest was 1990 (2°F) — a 50°F range across recorded history. Precipitation has occurred on 11% of recorded December 20th dates, with snow falling 5% of the time (heaviest snowfall: 15.7"). 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 20th in Longmont, CO? Bring layers as temperatures can vary throughout the day.
Warming Trend
2.7°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025warmest | 72° | 33° | 52° | — | — |
| 2024 | 63° | 21° | 42° | — | — |
| 2023 | 61° | 32° | 46° | — | — |
| 2022 | 47° | 15° | 31° | — | — |
| 2021 | 58° | 23° | 40° | — | — |
| 2020 | 47° | 15° | 31° | — | — |
| 2019 | 46° | 17° | 32° | — | — |
| 2018 | 50° | 21° | 36° | — | — |
| 2017 | 51° | 25° | 38° | — | — |
| 2016 | 60° | 31° | 45° | — | — |
| 2015 | 55° | 33° | 44° | — | — |
| 2014 | 50° | 26° | 38° | — | — |
| 2013 | 37° | 16° | 26° | — | — |
| 2012 | 49° | 8° | 28° | — | — |
| 2011 | 42° | 16° | 29° | 0.03" | — |
| 2010 | 59° | 34° | 46° | — | — |
| 2009 | 54° | 28° | 41° | — | — |
| 2008 | 36° | 16° | 26° | — | — |
| 2007 | 49° | 33° | 41° | — | — |
| 2006 | 31° | 24° | 27° | 2.87" | 15.7" |
| 2005 | 48° | 22° | 35° | — | — |
| 2004 | 53° | 32° | 43° | — | — |
| 2003 | 51° | 19° | 35° | — | — |
| 2002 | 39° | 15° | 27° | — | — |
| 2001 | 54° | 8° | 31° | — | — |
| 2000 | 57° | 9° | 33° | — | — |
| 1999 | 38° | 12° | 25° | — | — |
| 1998 | 9° | -6° | 2° | 0.15" | — |
| 1997 | 37° | 22° | 29° | — | — |
| 1996 | 29° | 1° | 15° | — | — |
| 1995 | 39° | 9° | 24° | — | — |
| 1994 | 53° | 16° | 34° | — | — |
| 1993 | 34° | 0° | 17° | 0.05" | — |
| 1992 | 21° | -8° | 7° | — | — |
| 1991 | 47° | 19° | 33° | — | — |
| 1990coldest | 16° | -11° | 2° | 0.53" | 2.5" |
| 1989 | 19° | -13° | 3° | — | — |
| 1988 | 42° | 17° | 30° | — | — |
| 1987 | 38° | 18° | 28° | — | — |
| 1986 | 45° | 18° | 31° | — | — |
| 1985 | 50° | 22° | 36° | — | — |
| 1984 | 57° | 14° | 36° | — | — |
| 1983 | 16° | 1° | 8° | 0.08" | 1" |
| 1982 | 56° | 22° | 39° | — | — |
| 1981 | 58° | 24° | 41° | — | — |
| 1980 | 21° | 17° | 19° | — | — |
| 1979 | 53° | 24° | 39° | — | — |
| 1978 | 45° | 17° | 31° | — | — |
| 1977 | 37° | 12° | 25° | — | — |
| 1976 | 45° | 10° | 27° | — | — |
| 1975 | 47° | 15° | 31° | — | — |
| 1974 | 43° | 15° | 29° | — | — |
| 1973 | 25° | -6° | 10° | — | — |
| 1972 | 49° | 19° | 34° | — | — |
| 1971 | 50° | 27° | 38° | — | — |
55 years of data from LONGMONT 2 ESE