Weather on May 21
Longmont, CO
55 Years of Data
Avg High
72°F
Avg Low
44°F
Warmest
2005
77°F avg
Coldest
2019
37°F avg
About This Date
May 21st in Longmont, CO typically brings pleasant spring weather, with average highs around 72°F and lows near 44°F — a 28°F daily swing. Over 54 years of records, the warmest May 21st was in 2005 (77°F average), while the coldest was 2019 (37°F) — a 40°F range across recorded history. Precipitation has occurred on 33% of recorded May 21st dates, with snow falling 4% of the time (heaviest snowfall: 1.9"). The last decade has been 5.9°F cooler on this date compared to 20-30 years ago.
The last decade has been 5.9°F cooler on this date compared to 20-30 years ago.
Planning for May 21st in Longmont, CO? Great weather for outdoor activities. Consider bringing rain gear or an umbrella.
Cooling Trend
0.5°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 71° | 45° | 58° | — | — |
| 2024 | 69° | 43° | 56° | 0.25" | — |
| 2023 | 70° | 45° | 57° | — | — |
| 2022 | 40° | 34° | 37° | 2.13" | 1.7" |
| 2021 | 78° | 49° | 63° | — | — |
| 2020 | 90° | 44° | 67° | — | — |
| 2019coldest | 42° | 32° | 37° | 2.01" | 1.9" |
| 2018 | 58° | 41° | 49° | 0.05" | — |
| 2017 | 67° | 35° | 51° | — | — |
| 2016 | 79° | 45° | 62° | — | — |
| 2015 | 50° | 39° | 45° | 0.18" | — |
| 2014 | 72° | 48° | 60° | 0.3" | — |
| 2013 | 68° | 38° | 53° | — | — |
| 2012 | 84° | 43° | 63° | — | — |
| 2011 | 66° | 38° | 52° | — | — |
| 2010 | 74° | 45° | 59° | — | — |
| 2008 | 81° | 53° | 67° | — | — |
| 2007 | 78° | 47° | 62° | 0.03" | — |
| 2006 | 90° | 52° | 71° | — | — |
| 2005warmest | 88° | 66° | 77° | — | — |
| 2004 | 74° | 54° | 64° | — | — |
| 2003 | 64° | 40° | 52° | — | — |
| 2002 | 66° | 40° | 53° | — | — |
| 2001 | 76° | 25° | 50° | 0.25" | — |
| 2000 | 69° | 40° | 54° | — | — |
| 1999 | 72° | 43° | 57° | 0.05" | — |
| 1998 | 87° | 49° | 68° | — | — |
| 1997 | 84° | 41° | 63° | — | — |
| 1996 | 73° | 42° | 58° | — | — |
| 1995 | 64° | 40° | 52° | 0.1" | — |
| 1994 | 85° | 40° | 62° | — | — |
| 1993 | 77° | 47° | 62° | 0.05" | — |
| 1992 | 88° | 50° | 69° | — | — |
| 1991 | 76° | 52° | 64° | 0.1" | — |
| 1990 | 82° | 43° | 62° | — | — |
| 1989 | 80° | 46° | 63° | — | — |
| 1988 | 55° | 38° | 46° | 0.08" | — |
| 1987 | 66° | 42° | 54° | 0.15" | — |
| 1986 | 85° | 47° | 66° | — | — |
| 1985 | 66° | 43° | 54° | — | — |
| 1984 | 89° | 50° | 70° | — | — |
| 1983 | 58° | 35° | 46° | 0.03" | — |
| 1982 | 70° | 41° | 55° | — | — |
| 1981 | 67° | 44° | 55° | — | — |
| 1980 | 78° | 47° | 62° | — | — |
| 1979 | 49° | 45° | 47° | 0.23" | — |
| 1978 | 72° | 48° | 60° | — | — |
| 1977 | 61° | 37° | 49° | 0.43" | — |
| 1976 | 76° | 52° | 64° | — | — |
| 1975 | 51° | 39° | 45° | 0.08" | — |
| 1974 | 65° | 42° | 53° | — | — |
| 1973 | 84° | 52° | 68° | — | — |
| 1972 | 85° | 46° | 65° | — | — |
| 1971 | 73° | 43° | 58° | — | — |
54 years of data from LONGMONT 2 ESE