Weather on April 21
San Mateo, CA
55 Years of Data
Avg High
66°F
Avg Low
49°F
Warmest
2009
74°F avg
Coldest
2008
50°F avg
About This Date
April 21st in San Mateo, CA typically brings mild spring weather, with average highs around 66°F and lows near 49°F. Over 55 years of records, the warmest April 21st was in 2009 (74°F average), while the coldest was 2008 (50°F) — a 24°F range across recorded history. Rain or other precipitation has occurred on about 16% of April 21st dates historically, with the wettest April 21st recording 0.51" 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 April 21st in San Mateo, CA? Great weather for outdoor activities.
Warming Trend
1.0°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 70° | 48° | 59° | — | — |
| 2024 | 72° | 53° | 62° | — | — |
| 2023 | 72° | 51° | 61° | — | — |
| 2022 | 64° | 54° | 59° | 0.43" | — |
| 2021 | 64° | 51° | 58° | — | — |
| 2020 | 65° | 52° | 58° | — | — |
| 2019 | 65° | 47° | 56° | — | — |
| 2018 | 75° | 50° | 63° | — | — |
| 2017 | 74° | 51° | 62° | — | — |
| 2016 | 70° | 60° | 65° | — | — |
| 2015 | 59° | 54° | 56° | — | — |
| 2014 | 69° | 52° | 60° | — | — |
| 2013 | 78° | 49° | 63° | — | — |
| 2012 | 80° | 56° | 68° | — | — |
| 2011 | 60° | 49° | 54° | 0.08" | — |
| 2010 | 57° | 49° | 53° | 0.1" | — |
| 2009warmest | 86° | 62° | 74° | — | — |
| 2008coldest | 56° | 44° | 50° | — | — |
| 2007 | 58° | 49° | 53° | 0.51" | — |
| 2006 | 63° | 52° | 57° | — | — |
| 2005 | 71° | 48° | 60° | — | — |
| 2004 | 62° | 51° | 57° | — | — |
| 2003 | 56° | 48° | 52° | 0.25" | — |
| 2002 | 66° | 47° | 56° | — | — |
| 2001 | 60° | 42° | 51° | — | — |
| 2000 | 61° | 53° | 57° | — | — |
| 1999 | 58° | 48° | 53° | — | — |
| 1998 | 79° | 49° | 64° | — | — |
| 1997 | 71° | 54° | 62° | — | — |
| 1996 | 67° | 48° | 57° | — | — |
| 1995 | 65° | 42° | 53° | — | — |
| 1994 | 63° | 50° | 56° | — | — |
| 1993 | 65° | 54° | 59° | — | — |
| 1992 | 62° | 52° | 57° | — | — |
| 1991 | 65° | 51° | 58° | 0.23" | — |
| 1990 | 60° | 52° | 56° | — | — |
| 1989 | 64° | 50° | 57° | 0.48" | — |
| 1988 | 63° | 49° | 56° | — | — |
| 1987 | 84° | 53° | 69° | — | — |
| 1986 | 72° | 49° | 60° | — | — |
| 1985 | 62° | 48° | 55° | 0.03" | — |
| 1984 | 69° | 47° | 58° | — | — |
| 1983 | 58° | 51° | 54° | — | — |
| 1982 | 78° | 54° | 66° | — | — |
| 1981 | 64° | 47° | 55° | — | — |
| 1980 | 59° | 46° | 53° | — | — |
| 1979 | 65° | 49° | 57° | — | — |
| 1978 | 64° | 43° | 53° | 0.05" | — |
| 1977 | 65° | 37° | 51° | — | — |
| 1976 | 69° | 39° | 54° | — | — |
| 1975 | 72° | 41° | 56° | — | — |
| 1974 | 63° | 44° | 53° | — | — |
| 1973 | 73° | 43° | 58° | — | — |
| 1972 | 67° | 46° | 56° | — | — |
| 1971 | 56° | 49° | 52° | — | — |
55 years of data from BURLINGAME