Weather on April 21
Boulder, CO
55 Years of Data
About This Date
April 21st in Boulder, CO typically brings mild spring weather, with average highs around 63°F and lows near 37°F — a 26°F daily swing. Over 56 years of records, the warmest April 21st was in 1989 (70°F average), while the coldest was 2021 (30°F) — a 40°F range across recorded history. Precipitation has occurred on 23% of recorded April 21st dates, with snow falling 5% of the time (heaviest snowfall: 2"). The last decade has been 1.1°F warmer on this date compared to 20-30 years ago.
The last decade has been 1.1°F warmer on this date compared to 20-30 years ago.
Planning for April 21st in Boulder, CO? Great weather for outdoor activities.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2026 | 84° | 50° | 67° | — | — |
| 2025 | 70° | 39° | 54° | — | — |
| 2024 | 63° | 32° | 47° | — | — |
| 2023 | 52° | 32° | 42° | — | — |
| 2022 | 79° | 45° | 62° | — | — |
| 2021coldest | 32° | 28° | 30° | — | — |
| 2020 | 66° | 39° | 53° | — | — |
| 2019 | 68° | 45° | 56° | — | — |
| 2018 | 41° | 32° | 37° | — | — |
| 2017 | 53° | 39° | 46° | 0.91" | — |
| 2016 | 65° | 37° | 51° | — | — |
| 2015 | 67° | 33° | 50° | — | — |
| 2014 | 66° | 41° | 54° | — | — |
| 2013 | 63° | 33° | 48° | — | — |
| 2012 | 75° | 48° | 62° | — | — |
| 2011 | 70° | 37° | 53° | 0.51" | — |
| 2010 | 59° | 43° | 51° | 0.08" | — |
| 2009 | 75° | 42° | 59° | — | — |
| 2008 | 68° | 32° | 50° | — | — |
| 2007 | 65° | 43° | 54° | — | — |
| 2006 | 74° | 36° | 55° | — | — |
| 2005 | 60° | 31° | 45° | 0.25" | — |
| 2004 | 59° | 35° | 47° | 0.51" | — |
| 2003 | 61° | 33° | 47° | — | — |
| 2002 | 56° | 32° | 44° | — | — |
| 2001 | 59° | 34° | 46° | 0.05" | — |
| 2000 | 75° | 36° | 55° | — | — |
| 1999 | 66° | 44° | 55° | 0.03" | — |
| 1998 | 58° | 34° | 46° | — | — |
| 1997 | 68° | 48° | 58° | — | — |
| 1996 | 52° | 30° | 41° | — | — |
| 1995 | 41° | 32° | 37° | 1.3" | 0.9" |
| 1994 | 77° | 38° | 57° | — | — |
| 1993 | 62° | 27° | 44° | — | — |
| 1992 | 67° | 30° | 48° | — | — |
| 1991 | 53° | 39° | 46° | 0.3" | — |
| 1990 | 72° | 41° | 56° | — | — |
| 1989warmest | 88° | 53° | 70° | — | — |
| 1988 | 71° | 51° | 61° | — | — |
| 1987 | 59° | 25° | 42° | 0.05" | 0.2" |
| 1986 | 65° | 40° | 52° | 0.05" | — |
| 1985 | 60° | 37° | 49° | — | — |
| 1984 | 44° | 31° | 37° | 0.81" | 2" |
| 1983 | 54° | 43° | 48° | 1.63" | — |
| 1982 | 54° | 18° | 36° | — | — |
| 1981 | 73° | 46° | 60° | — | — |
| 1980 | 83° | 49° | 66° | — | — |
| 1979 | 72° | 36° | 54° | — | — |
| 1978 | 62° | 31° | 46° | — | — |
| 1977 | 60° | 29° | 44° | — | — |
| 1976 | 66° | 41° | 54° | — | — |
| 1975 | 61° | 36° | 48° | — | — |
| 1974 | 60° | 37° | 49° | — | — |
| 1973 | 52° | 32° | 42° | — | — |
| 1972 | 61° | 31° | 46° | — | — |
| 1971 | 61° | 37° | 49° | — | — |
Boulder, CO Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
Boulder, CO Monthly Precipitation
Average rainfall and snowfall per month, in inches.
Boulder, 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 Boulder, CO
Boulder, CO has no months that meet our "pleasant" threshold — every season has tradeoffs.