Weather on August 21
Boston, MA
55 Years of Data
Avg High
79°F
Avg Low
63°F
Warmest
1976
82°F avg
Coldest
2007
61°F avg
About This Date
August 21st in Boston, MA typically brings pleasant summer weather, with average highs around 79°F and lows near 63°F. Over 55 years of records, the warmest August 21st was in 1976 (82°F average), while the coldest was 2007 (61°F) — a 21°F range across recorded history. Rain or other precipitation has occurred on about 25% of August 21st dates historically, with the wettest August 21st recording 4.37" of rain. The last decade has been 3.2°F warmer on this date compared to 20-30 years ago.
The last decade has been 3.2°F warmer on this date compared to 20-30 years ago.
Planning for August 21st in Boston, MA? Great weather for outdoor activities.
Warming Trend
0.8°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 69° | 57° | 63° | — | — |
| 2024 | 76° | 58° | 67° | — | — |
| 2023 | 86° | 68° | 77° | 0.71" | — |
| 2022 | 89° | 68° | 79° | — | — |
| 2021 | 83° | 72° | 77° | — | — |
| 2020 | 89° | 63° | 76° | — | — |
| 2019 | 88° | 69° | 78° | 0.2" | — |
| 2018 | 72° | 65° | 68° | — | — |
| 2017 | 87° | 69° | 78° | — | — |
| 2016 | 78° | 65° | 71° | 0.03" | — |
| 2015 | 83° | 67° | 75° | 1.6" | — |
| 2014 | 72° | 60° | 66° | — | — |
| 2013 | 89° | 67° | 78° | — | — |
| 2012 | 83° | 66° | 74° | — | — |
| 2011 | 86° | 69° | 78° | — | — |
| 2010 | 73° | 62° | 68° | — | — |
| 2009 | 90° | 72° | 81° | — | — |
| 2008 | 78° | 59° | 69° | — | — |
| 2007coldest | 67° | 55° | 61° | — | — |
| 2006 | 77° | 62° | 70° | — | — |
| 2005 | 88° | 69° | 78° | 0.05" | — |
| 2004 | 79° | 63° | 71° | 2.67" | — |
| 2003 | 90° | 73° | 81° | — | — |
| 2002 | 76° | 65° | 70° | — | — |
| 2001 | 72° | 64° | 68° | — | — |
| 2000 | 75° | 56° | 65° | — | — |
| 1999 | 66° | 59° | 63° | 0.3" | — |
| 1998 | 76° | 64° | 70° | — | — |
| 1997 | 64° | 60° | 62° | 2.16" | — |
| 1996 | 84° | 65° | 74° | — | — |
| 1995 | 94° | 59° | 76° | — | — |
| 1994 | 85° | 66° | 75° | 1.98" | — |
| 1993 | 75° | 62° | 69° | — | — |
| 1992 | 80° | 57° | 69° | — | — |
| 1991 | 66° | 58° | 62° | 4.37" | — |
| 1990 | 69° | 61° | 65° | — | — |
| 1989 | 87° | 70° | 78° | 0.89" | — |
| 1988 | 81° | 59° | 70° | — | — |
| 1987 | 84° | 64° | 74° | — | — |
| 1986 | 70° | 60° | 65° | 0.1" | — |
| 1985 | 78° | 63° | 70° | 0.03" | — |
| 1984 | 77° | 56° | 66° | — | — |
| 1983 | 85° | 67° | 76° | — | — |
| 1982 | 70° | 54° | 62° | — | — |
| 1981 | 76° | 56° | 66° | — | — |
| 1980 | 67° | 59° | 63° | — | — |
| 1979 | 71° | 62° | 67° | — | — |
| 1978 | 72° | 63° | 67° | — | — |
| 1977 | 69° | 56° | 62° | — | — |
| 1976warmest | 93° | 71° | 82° | — | — |
| 1975 | 82° | 60° | 71° | 0.05" | — |
| 1974 | 77° | 62° | 70° | — | — |
| 1973 | 72° | 62° | 67° | — | — |
| 1972 | 85° | 63° | 74° | — | — |
| 1971 | 87° | 71° | 79° | — | — |
55 years of data from BOSTON