Weather on March 21
Simi Valley, CA
55 Years of Data
Avg High
68°F
Avg Low
50°F
Warmest
2026
79°F avg
Coldest
2011
47°F avg
About This Date
March 21st in Simi Valley, CA typically brings mild spring weather, with average highs around 68°F and lows near 50°F. Over 31 years of records, the warmest March 21st was in 2026 (79°F average), while the coldest was 2011 (47°F) — a 32°F range across recorded history. This date has historically been dry, with little recorded precipitation. The last decade has been 1.6°F cooler on this date compared to 20-30 years ago.
The last decade has been 1.6°F cooler on this date compared to 20-30 years ago.
Planning for March 21st in Simi Valley, CA? Great weather for outdoor activities.
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2026warmest | 90° | 68° | 79° | — | — |
| 2025 | 72° | 56° | 64° | — | — |
| 2024 | 72° | 47° | 59° | — | — |
| 2023 | 53° | 42° | 48° | — | — |
| 2022 | 78° | 60° | 69° | — | — |
| 2021 | 66° | 47° | 56° | — | — |
| 2020 | 64° | 47° | 55° | — | — |
| 2019 | 58° | 44° | 51° | — | — |
| 2018 | 58° | 49° | 53° | — | — |
| 2017 | 55° | 50° | 53° | — | — |
| 2016 | 66° | 50° | 58° | — | — |
| 2015 | 78° | 54° | 66° | — | — |
| 2014 | 69° | 46° | 58° | — | — |
| 2013 | 75° | 56° | 65° | — | — |
| 2012 | 72° | 46° | 59° | — | — |
| 2011coldest | 52° | 43° | 47° | — | — |
| 2010 | 77° | 50° | 64° | — | — |
| 2009 | 57° | 50° | 54° | — | — |
| 2008 | 79° | 57° | 68° | — | — |
| 2007 | 59° | 48° | 54° | — | — |
| 2006 | 55° | 41° | 48° | — | — |
| 2005 | 64° | 46° | 55° | — | — |
| 2004 | 73° | 52° | 62° | — | — |
| 2003 | 72° | 52° | 62° | — | — |
| 2002 | 77° | 48° | 63° | — | — |
| 2001 | 74° | 50° | 62° | — | — |
| 2000 | 67° | 49° | 58° | — | — |
| 1999 | 57° | 44° | 51° | — | — |
| 1998 | 67° | 48° | 57° | — | — |
| 1997 | 85° | 57° | 71° | — | — |
| 1996 | 73° | 49° | 61° | — | — |
31 years of data from SIMI VALLEY CALIFORNIA