Weather on March 21
Longmont, CO
55 Years of Data
About This Date
March 21st in Longmont, CO typically brings cool spring weather, with average highs around 58°F and lows near 27°F — a 31°F daily swing. Over 56 years of records, the warmest March 21st was in 2026 (66°F average), while the coldest was 1974 (19°F) — a 47°F range across recorded history. Precipitation has occurred on 7% of recorded March 21st dates, with snow falling 2% of the time (heaviest snowfall: 1.2"). The last decade has been 2.4°F warmer on this date compared to 20-30 years ago.
The last decade has been 2.4°F warmer on this date compared to 20-30 years ago.
Planning for March 21st in Longmont, CO? Bring layers as temperatures can vary throughout the day.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2026warmest | 89° | 42° | 66° | — | — |
| 2025 | 60° | 23° | 42° | — | — |
| 2024 | 63° | 30° | 46° | — | — |
| 2023 | 60° | 28° | 44° | — | — |
| 2022 | 69° | 30° | 50° | — | — |
| 2021 | 57° | 30° | 44° | — | — |
| 2020 | 26° | 21° | 24° | — | — |
| 2019 | 63° | 22° | 42° | — | — |
| 2018 | 55° | 27° | 41° | — | — |
| 2017 | 69° | 36° | 52° | — | — |
| 2016 | 72° | 33° | 52° | — | — |
| 2015 | 71° | 35° | 53° | — | — |
| 2014 | 58° | 28° | 43° | — | — |
| 2013 | 60° | 35° | 48° | — | — |
| 2012 | 65° | 26° | 45° | — | — |
| 2011 | 73° | 33° | 53° | — | — |
| 2010 | 59° | 19° | 39° | — | — |
| 2009 | 73° | 34° | 53° | — | — |
| 2008 | 55° | 34° | 44° | — | — |
| 2007 | 71° | 48° | 60° | — | — |
| 2006 | 26° | 12° | 19° | 0.08" | 1.2" |
| 2005 | 52° | 36° | 44° | — | — |
| 2004 | 78° | 30° | 54° | — | — |
| 2003 | 48° | 34° | 41° | — | — |
| 2002 | 66° | 8° | 37° | — | — |
| 2001 | 69° | 30° | 50° | — | — |
| 2000 | 34° | 25° | 29° | 0.38" | — |
| 1999 | 70° | 21° | 45° | — | — |
| 1998 | 47° | 16° | 31° | — | — |
| 1997 | 85° | 37° | 61° | — | — |
| 1996 | 60° | 22° | 41° | — | — |
| 1995 | 67° | 35° | 51° | — | — |
| 1994 | 50° | 21° | 36° | — | — |
| 1993 | 54° | 30° | 42° | — | — |
| 1992 | 62° | 26° | 44° | — | — |
| 1991 | 65° | 25° | 45° | — | — |
| 1990 | 72° | 36° | 54° | — | — |
| 1989 | 31° | 15° | 23° | — | — |
| 1988 | 69° | 34° | 51° | — | — |
| 1987 | 47° | 23° | 35° | — | — |
| 1986 | 70° | 25° | 47° | — | — |
| 1985 | 66° | 27° | 46° | — | — |
| 1984 | 59° | 25° | 42° | — | — |
| 1983 | 30° | 10° | 20° | — | — |
| 1982 | 52° | 16° | 34° | — | — |
| 1981 | 47° | 22° | 34° | — | — |
| 1980 | 54° | 21° | 37° | — | — |
| 1979 | 36° | 31° | 33° | — | — |
| 1978 | 66° | 29° | 47° | — | — |
| 1977 | 47° | 16° | 31° | — | — |
| 1976 | 48° | 32° | 40° | — | — |
| 1975 | 72° | 37° | 54° | 0.03" | — |
| 1974coldest | 24° | 14° | 19° | 0.03" | — |
| 1973 | 54° | 31° | 42° | — | — |
| 1972 | 57° | 22° | 39° | — | — |
| 1971 | 67° | 30° | 48° | — | — |
Longmont, CO Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
Longmont, CO Monthly Precipitation
Average rainfall and snowfall per month, in inches.
Longmont, CO Daily Temperature Calendar
Average daily high temperature for every day of the year. Each cell is the climatological mean for that calendar day across 55 years of NOAA data.
Best Time to Visit Longmont, CO
Longmont, CO has no months that meet our "pleasant" threshold — every season has tradeoffs.