Weather on December 21
Sunnyvale, CA
55 Years of Data
Avg High
58°F
Avg Low
43°F
Warmest
2005
63°F avg
Coldest
1990
34°F avg
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.
Warming Trend
0.6°F per decade on this date
| 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" | — |
55 years of data from MOFFETT FED AIRFIELD