Weather on June 21
Boulder, CO
55 Years of Data
Avg High
85°F
Avg Low
54°F
Warmest
2025
81°F avg
Coldest
2004
57°F avg
About This Date
June 21st in Boulder, CO typically brings warm summer weather, with average highs around 85°F and lows near 54°F — a 31°F daily swing. Over 55 years of records, the warmest June 21st was in 2025 (81°F average), while the coldest was 2004 (57°F) — a 24°F range across recorded history. Rain or other precipitation has occurred on about 27% of June 21st dates historically, with the wettest June 21st recording 1.37" of rain. The last decade has been 3.4°F warmer on this date compared to 20-30 years ago.
The last decade has been 3.4°F warmer on this date compared to 20-30 years ago.
Planning for June 21st in Boulder, CO? Stay hydrated and seek shade during peak afternoon hours.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025warmest | 97° | 66° | 81° | — | — |
| 2024 | 84° | 61° | 72° | — | — |
| 2023 | 81° | 55° | 68° | — | — |
| 2022 | 82° | 54° | 68° | — | — |
| 2021 | 72° | 50° | 61° | 0.13" | — |
| 2020 | 79° | 59° | 69° | — | — |
| 2019 | 66° | 50° | 58° | — | — |
| 2018 | 79° | 54° | 66° | — | — |
| 2017 | 98° | 63° | 80° | 0.18" | — |
| 2016 | 99° | 56° | 77° | — | — |
| 2015 | 92° | 56° | 74° | — | — |
| 2014 | 86° | 55° | 71° | — | — |
| 2013 | 92° | 57° | 74° | — | — |
| 2012 | 88° | 54° | 71° | — | — |
| 2011 | 76° | 51° | 63° | — | — |
| 2010 | 81° | 54° | 67° | 0.18" | — |
| 2009 | 80° | 50° | 65° | 0.05" | — |
| 2008 | 86° | 49° | 67° | — | — |
| 2007 | 95° | 60° | 78° | — | — |
| 2006 | 89° | 57° | 73° | 0.15" | — |
| 2005 | 89° | 57° | 73° | — | — |
| 2004coldest | 68° | 46° | 57° | 1.37" | — |
| 2003 | 83° | 52° | 67° | 0.1" | — |
| 2002 | 89° | 59° | 74° | — | — |
| 2001 | 76° | 48° | 62° | — | — |
| 2000 | 82° | 41° | 62° | — | — |
| 1999 | 83° | 53° | 68° | — | — |
| 1998 | 74° | 49° | 61° | 0.2" | — |
| 1997 | 86° | 58° | 72° | — | — |
| 1996 | 80° | 59° | 70° | 1.35" | — |
| 1995 | 84° | 53° | 69° | — | — |
| 1994 | 79° | 54° | 66° | 0.46" | — |
| 1993 | 82° | 52° | 67° | 0.18" | — |
| 1992 | 76° | 49° | 62° | 0.05" | — |
| 1991 | 75° | 56° | 65° | 0.03" | — |
| 1990 | 82° | 53° | 68° | — | — |
| 1989 | 85° | 51° | 68° | — | — |
| 1988 | 92° | 64° | 78° | 0.46" | — |
| 1987 | 86° | 59° | 73° | — | — |
| 1986 | 91° | 54° | 72° | — | — |
| 1985 | 83° | 60° | 71° | — | — |
| 1984 | 90° | 50° | 70° | — | — |
| 1983 | 91° | 51° | 71° | — | — |
| 1982 | 82° | 50° | 66° | — | — |
| 1981 | 91° | 58° | 74° | — | — |
| 1980 | 90° | 56° | 73° | — | — |
| 1979 | 87° | 49° | 68° | — | — |
| 1978 | 93° | 52° | 72° | — | — |
| 1977 | 81° | 53° | 67° | 0.05" | — |
| 1976 | 90° | 63° | 76° | — | — |
| 1975 | 79° | 49° | 64° | — | — |
| 1974 | 92° | 61° | 76° | — | — |
| 1973 | 81° | 47° | 64° | — | — |
| 1972 | 86° | 50° | 68° | — | — |
| 1971 | 91° | 57° | 74° | — | — |
55 years of data from BOULDER MUNI AP