Weather on August 21
San Mateo, CA
55 Years of Data
Avg High
73°F
Avg Low
57°F
Warmest
1976
70°F avg
Coldest
1986
59°F avg
About This Date
August 21st in San Mateo, CA typically brings pleasant summer weather, with average highs around 73°F and lows near 57°F. Over 55 years of records, the warmest August 21st was in 1976 (70°F average), while the coldest was 1986 (59°F) — a 11°F range across recorded history. Rain or other precipitation has occurred on about 2% of August 21st dates historically. The last decade has been 2.6°F warmer on this date compared to 20-30 years ago.
The last decade has been 2.6°F warmer on this date compared to 20-30 years ago.
Planning for August 21st in San Mateo, CA? Great weather for outdoor activities.
Warming Trend
0.3°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 81° | 57° | 69° | — | — |
| 2024 | 71° | 56° | 63° | — | — |
| 2023 | 75° | 63° | 69° | 0.08" | — |
| 2022 | 78° | 57° | 68° | — | — |
| 2021 | 71° | 59° | 65° | — | — |
| 2020 | 80° | 58° | 69° | — | — |
| 2019 | 79° | 61° | 70° | — | — |
| 2018 | 67° | 55° | 61° | — | — |
| 2017 | 75° | 61° | 68° | — | — |
| 2016 | 69° | 58° | 63° | — | — |
| 2015 | 71° | 59° | 65° | — | — |
| 2014 | 74° | 61° | 67° | — | — |
| 2013 | 72° | 58° | 65° | — | — |
| 2012 | 65° | 54° | 59° | — | — |
| 2011 | 68° | 57° | 63° | — | — |
| 2010 | 65° | 56° | 60° | — | — |
| 2009 | 79° | 57° | 68° | — | — |
| 2008 | 72° | 59° | 65° | — | — |
| 2007 | 77° | 59° | 68° | — | — |
| 2006 | 66° | 55° | 61° | — | — |
| 2005 | 65° | 56° | 60° | — | — |
| 2004 | 74° | 61° | 67° | — | — |
| 2003 | 75° | 62° | 69° | — | — |
| 2002 | 67° | 56° | 61° | — | — |
| 2001 | 65° | 53° | 59° | — | — |
| 2000 | 70° | 53° | 61° | — | — |
| 1999 | 78° | 56° | 67° | — | — |
| 1998 | 70° | 57° | 63° | — | — |
| 1997 | 78° | 59° | 69° | — | — |
| 1996 | 75° | 52° | 63° | — | — |
| 1995 | 68° | 55° | 62° | — | — |
| 1994 | 69° | 55° | 62° | — | — |
| 1993 | 82° | 55° | 69° | — | — |
| 1992 | 69° | 54° | 61° | — | — |
| 1991 | 68° | 57° | 63° | — | — |
| 1990 | 71° | 58° | 64° | — | — |
| 1989 | 75° | 58° | 66° | — | — |
| 1988 | 74° | 56° | 65° | — | — |
| 1987 | 72° | 55° | 63° | — | — |
| 1986coldest | 65° | 53° | 59° | — | — |
| 1985 | 68° | 56° | 62° | — | — |
| 1984 | 73° | 54° | 63° | — | — |
| 1983 | 76° | 61° | 68° | — | — |
| 1982 | 74° | 53° | 63° | — | — |
| 1981 | 76° | 54° | 65° | — | — |
| 1980 | 66° | 53° | 60° | — | — |
| 1979 | 74° | 59° | 66° | — | — |
| 1978 | — | 56° | — | — | — |
| 1977 | 70° | 56° | 63° | — | — |
| 1976warmest | 80° | 60° | 70° | — | — |
| 1975 | 74° | 52° | 63° | — | — |
| 1974 | 82° | 50° | 66° | — | — |
| 1973 | 70° | 51° | 60° | — | — |
| 1972 | 78° | 56° | 67° | — | — |
| 1971 | 74° | 61° | 67° | — | — |
55 years of data from BURLINGAME