Weather on April 21
San Mateo, CA
55 Years of Data
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 56 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 18% of April 21st dates historically, with the wettest April 21st recording 0.56" of rain. The last decade has been 3.1°F warmer on this date compared to 20-30 years ago.
The last decade has been 3.1°F warmer on this date compared to 20-30 years ago.
Planning for April 21st in San Mateo, CA? Great weather for outdoor activities.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2026 | 63° | 52° | 57° | 0.56" | — |
| 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° | — | — |
San Mateo, CA Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
San Mateo, CA Monthly Precipitation
Average rainfall per month, in inches.
San Mateo, CA Daily Temperature Calendar
Average daily high temperature for every day of the year. Each cell is the climatological mean for that calendar day across 55 years of NOAA data.
Best Time to Visit San Mateo, CA
San Mateo, CA has no months that meet our "pleasant" threshold — every season has tradeoffs.