Weather on August 21
Vacaville, CA
55 Years of Data
Avg High
91°F
Avg Low
57°F
Warmest
2025
82°F avg
Coldest
1987
67°F avg
About This Date
August 21st in Vacaville, CA typically brings hot summer weather, with average highs around 91°F and lows near 57°F — a 34°F daily swing. Over 55 years of records, the warmest August 21st was in 2025 (82°F average), while the coldest was 1987 (67°F) — a 15°F range across recorded history. Rain or other precipitation has occurred on about 4% of August 21st dates historically, with the wettest August 21st recording 0.51" of rain. The last decade has been 1.3°F warmer on this date compared to 20-30 years ago.
The last decade has been 1.3°F warmer on this date compared to 20-30 years ago.
Planning for August 21st in Vacaville, CA? Stay hydrated and seek shade during peak afternoon hours.
Warming Trend
0.8°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025warmest | 104° | 59° | 82° | — | — |
| 2024 | 91° | 62° | 77° | — | — |
| 2023 | 81° | 67° | 74° | 0.03" | — |
| 2022 | 91° | 67° | 79° | — | — |
| 2021 | 77° | 59° | 68° | — | — |
| 2020 | 96° | 58° | 77° | — | — |
| 2019 | 98° | 57° | 78° | — | — |
| 2018 | 80° | 56° | 68° | — | — |
| 2017 | 88° | 63° | 75° | — | — |
| 2016 | 95° | 60° | 78° | — | — |
| 2015 | 89° | 58° | 73° | — | — |
| 2014 | 89° | 57° | 73° | — | — |
| 2013 | 92° | 63° | 77° | — | — |
| 2012 | 97° | 57° | 77° | — | — |
| 2011 | 86° | 55° | 71° | — | — |
| 2010 | 83° | 57° | 70° | — | — |
| 2009 | 102° | 60° | 81° | — | — |
| 2008 | 91° | 67° | 79° | — | — |
| 2007 | 100° | 63° | 81° | — | — |
| 2006 | 92° | 57° | 74° | — | — |
| 2005 | 96° | 56° | 76° | — | — |
| 2004 | 95° | 61° | 78° | — | — |
| 2003 | 89° | 65° | 77° | 0.51" | — |
| 2002 | 90° | 52° | 71° | — | — |
| 2001 | 85° | 52° | 68° | — | — |
| 2000 | 94° | 57° | 75° | — | — |
| 1999 | 96° | 58° | 77° | — | — |
| 1998 | 82° | 54° | 68° | — | — |
| 1997 | 93° | 59° | 76° | — | — |
| 1996 | 96° | 57° | 77° | — | — |
| 1995 | 80° | 56° | 68° | — | — |
| 1994 | 93° | 53° | 73° | — | — |
| 1993 | 97° | 58° | 77° | — | — |
| 1992 | 102° | 60° | 81° | — | — |
| 1991 | 94° | 50° | 72° | — | — |
| 1990 | 90° | 57° | 73° | — | — |
| 1989 | 88° | 56° | 72° | — | — |
| 1988 | 90° | 62° | 76° | — | — |
| 1987coldest | 85° | 50° | 67° | — | — |
| 1986 | 92° | 50° | 71° | — | — |
| 1985 | 86° | 53° | 70° | — | — |
| 1984 | 90° | 52° | 71° | — | — |
| 1983 | 83° | 60° | 71° | — | — |
| 1982 | 99° | 59° | 79° | — | — |
| 1981 | 92° | 49° | 70° | — | — |
| 1980 | 93° | 52° | 72° | — | — |
| 1979 | 82° | 59° | 71° | — | — |
| 1978 | 85° | 59° | 72° | — | — |
| 1977 | 94° | 55° | 74° | — | — |
| 1976 | 88° | 59° | 73° | — | — |
| 1975 | 91° | 55° | 73° | — | — |
| 1974 | 98° | 52° | 75° | — | — |
| 1973 | 93° | 53° | 73° | — | — |
| 1972 | 96° | 51° | 74° | — | — |
| 1971 | 88° | 50° | 69° | — | — |
55 years of data from VACAVILLE/NUT TREE AP ASOS