Weather on December 31
Simi Valley, CA
55 Years of Data
Avg High
62°F
Avg Low
48°F
Warmest
1997
69°F avg
Coldest
2014
42°F avg
About This Date
December 31st in Simi Valley, CA typically brings mild winter weather, with average highs around 62°F and lows near 48°F. Over 30 years of records, the warmest December 31st was in 1997 (69°F average), while the coldest was 2014 (42°F) — a 27°F range across recorded history. This date has historically been dry, with little recorded precipitation. The last decade has been 1.9°F cooler on this date compared to 20-30 years ago.
The last decade has been 1.9°F cooler on this date compared to 20-30 years ago.
Planning for December 31st in Simi Valley, CA? Great weather for outdoor activities.
Cooling Trend
1.6°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 64° | 50° | 57° | — | — |
| 2024 | 70° | 49° | 59° | — | — |
| 2022 | 54° | 51° | 52° | — | — |
| 2021 | 60° | 43° | 51° | — | — |
| 2020 | 58° | 48° | 53° | — | — |
| 2019 | 61° | 53° | 57° | — | — |
| 2018 | 56° | 45° | 50° | — | — |
| 2017 | 71° | 53° | 62° | — | — |
| 2016 | 50° | 41° | 46° | — | — |
| 2015 | 57° | 45° | 51° | — | — |
| 2014coldest | 47° | 37° | 42° | — | — |
| 2013 | 78° | 56° | 67° | — | — |
| 2012 | 58° | 41° | 49° | — | — |
| 2011 | 79° | 48° | 63° | — | — |
| 2010 | 54° | 39° | 46° | — | — |
| 2009 | 62° | 46° | 54° | — | — |
| 2008 | 66° | 45° | 55° | — | — |
| 2007 | 64° | 54° | 59° | — | — |
| 2006 | 59° | 39° | 49° | — | — |
| 2005 | 57° | 48° | 53° | — | — |
| 2004 | 55° | 48° | 52° | — | — |
| 2003 | 63° | 41° | 52° | — | — |
| 2002 | 55° | 43° | 49° | — | — |
| 2001 | 59° | 52° | 55° | — | — |
| 2000 | 75° | 55° | 65° | — | — |
| 1999 | 52° | 44° | 48° | — | — |
| 1998 | 69° | 50° | 60° | — | — |
| 1997warmest | 79° | 60° | 69° | — | — |
| 1996 | 63° | 52° | 57° | — | — |
| 1995 | 64° | 61° | 62° | — | — |
30 years of data from SIMI VALLEY CALIFORNIA