Weather on December 21
Sunnyvale, CA
55 Years of Data
About This Date
December 21st in Sunnyvale, CA typically brings cool winter weather, with average highs around 58°F and lows near 43°F. Over 55 years of records, the warmest December 21st was in 2005 (63°F average), while the coldest was 1990 (34°F) — a 29°F range across recorded history. Rain or other precipitation has occurred on about 40% of December 21st dates historically, with the wettest December 21st recording 4.01" of rain. The last decade has been 1.5°F warmer on this date compared to 20-30 years ago.
The last decade has been 1.5°F warmer on this date compared to 20-30 years ago.
Planning for December 21st in Sunnyvale, CA? Bring layers as temperatures can vary throughout the day. Consider bringing rain gear or an umbrella.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 64° | 61° | 63° | — | — |
| 2024 | 65° | 51° | 58° | — | — |
| 2023 | 61° | 48° | 54° | — | — |
| 2022 | 61° | 38° | 49° | — | — |
| 2021 | 60° | 37° | 49° | 0.25" | — |
| 2020 | 60° | 34° | 47° | — | — |
| 2019 | 60° | 44° | 52° | — | — |
| 2018 | 59° | 50° | 55° | 0.03" | — |
| 2017 | 58° | 36° | 47° | — | — |
| 2016 | 64° | 41° | 53° | — | — |
| 2015 | 60° | 51° | 56° | 1.02" | — |
| 2014 | 65° | 56° | 60° | — | — |
| 2013 | 60° | 37° | 49° | — | — |
| 2012 | 57° | 52° | 54° | 0.05" | — |
| 2011 | 65° | 39° | 52° | — | — |
| 2010 | 61° | 49° | 55° | 0.38" | — |
| 2009 | 59° | 48° | 54° | 0.3" | — |
| 2008 | 52° | 43° | 47° | 0.2" | — |
| 2007 | 53° | 38° | 45° | — | — |
| 2006 | 53° | 39° | 46° | 0.56" | — |
| 2005warmest | 68° | 57° | 63° | 0.74" | — |
| 2004 | 65° | 42° | 53° | — | — |
| 2003 | 60° | 50° | 55° | 0.15" | — |
| 2002 | 59° | 47° | 53° | 0.05" | — |
| 2001 | 53° | 42° | 48° | 0.05" | — |
| 2000 | 61° | 37° | 49° | — | — |
| 1999 | 70° | 42° | 56° | — | — |
| 1998 | 44° | 29° | 36° | — | — |
| 1997 | 55° | 42° | 49° | — | — |
| 1996 | 51° | 48° | 50° | 4.01" | — |
| 1995 | 58° | 40° | 49° | — | — |
| 1994 | 52° | 37° | 44° | — | — |
| 1993 | 47° | 34° | 40° | — | — |
| 1992 | 58° | 45° | 51° | — | — |
| 1991 | 58° | 37° | 47° | — | — |
| 1990coldest | 39° | 28° | 34° | — | — |
| 1989 | 58° | 43° | 50° | — | — |
| 1988 | 56° | 41° | 48° | 0.46" | — |
| 1987 | 55° | 43° | 49° | — | — |
| 1986 | 58° | 40° | 49° | — | — |
| 1985 | 56° | 37° | 46° | — | — |
| 1984 | 58° | 38° | 48° | — | — |
| 1983 | 50° | 41° | 46° | — | — |
| 1982 | 59° | 53° | 56° | 1.57" | — |
| 1981 | 60° | 48° | 54° | 0.05" | — |
| 1980 | 61° | 50° | 55° | 0.84" | — |
| 1979 | 59° | 48° | 54° | 0.25" | — |
| 1978 | 56° | 33° | 44° | — | — |
| 1977 | 69° | 53° | 61° | 0.76" | — |
| 1976 | 58° | 34° | 46° | — | — |
| 1975 | 62° | 40° | 51° | 0.33" | — |
| 1974 | 57° | 42° | 50° | — | — |
| 1973 | 62° | 48° | 55° | 1.19" | — |
| 1972 | 62° | 53° | 58° | — | — |
| 1971 | 59° | 40° | 49° | 0.97" | — |
Sunnyvale, CA Temperature Range by Month
Average monthly highs and lows. The shaded band shows the typical daily temperature range.
Sunnyvale, CA Monthly Precipitation
Average rainfall per month, in inches.
Sunnyvale, 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 Sunnyvale, CA
Most pleasant months in Sunnyvale, CA: July, August.