Weather on December 20
Simi Valley, CA
55 Years of Data
Avg High
65°F
Avg Low
49°F
Warmest
1999
70°F avg
Coldest
1998
43°F avg
About This Date
December 20th in Simi Valley, CA typically brings mild winter weather, with average highs around 65°F and lows near 49°F. Over 31 years of records, the warmest December 20th was in 1999 (70°F average), while the coldest was 1998 (43°F) — a 27°F range across recorded history. This date has historically been dry, with little recorded precipitation. 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 December 20th in Simi Valley, CA? Great weather for outdoor activities.
Warming Trend
1.7°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 68° | 52° | 60° | — | — |
| 2024 | 74° | 60° | 67° | — | — |
| 2023 | 57° | 54° | 55° | — | — |
| 2022 | 66° | 53° | 60° | — | — |
| 2021 | 63° | 48° | 55° | — | — |
| 2020 | 80° | 59° | 70° | — | — |
| 2019 | 71° | 52° | 61° | — | — |
| 2018 | 78° | 63° | 70° | — | — |
| 2017 | 59° | 44° | 52° | — | — |
| 2016 | 70° | 51° | 60° | — | — |
| 2015 | 56° | 43° | 49° | — | — |
| 2014 | 58° | 49° | 53° | — | — |
| 2013 | 61° | 46° | 53° | — | — |
| 2012 | 60° | 41° | 51° | — | — |
| 2011 | 66° | 43° | 54° | — | — |
| 2010 | 54° | 49° | 51° | — | — |
| 2009 | 69° | 57° | 63° | — | — |
| 2008 | 61° | 39° | 50° | — | — |
| 2007 | 55° | 48° | 52° | — | — |
| 2006 | 57° | 34° | 45° | — | — |
| 2005 | 75° | 59° | 67° | — | — |
| 2004 | 72° | 48° | 60° | — | — |
| 2003 | 61° | 48° | 54° | — | — |
| 2002 | 55° | 46° | 51° | — | — |
| 2001 | 55° | 45° | 50° | — | — |
| 2000 | 80° | 57° | 69° | — | — |
| 1999warmest | 76° | 64° | 70° | — | — |
| 1998coldest | 50° | 36° | 43° | — | — |
| 1997 | 66° | 47° | 56° | — | — |
| 1996 | 71° | 46° | 59° | — | — |
| 1995 | 61° | 46° | 53° | — | — |
31 years of data from SIMI VALLEY CALIFORNIA