Weather on October 21
Simi Valley, CA
55 Years of Data
Avg High
79°F
Avg Low
59°F
Warmest
1999
83°F avg
Coldest
2004
57°F avg
About This Date
October 21st in Simi Valley, CA typically brings pleasant fall weather, with average highs around 79°F and lows near 59°F. Over 31 years of records, the warmest October 21st was in 1999 (83°F average), while the coldest was 2004 (57°F) — a 26°F range across recorded history. This date has historically been dry, with little recorded precipitation. The last decade has been 6.7°F warmer on this date compared to 20-30 years ago.
The last decade has been 6.7°F warmer on this date compared to 20-30 years ago.
Planning for October 21st in Simi Valley, CA? Great weather for outdoor activities.
Warming Trend
2.9°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 84° | 54° | 69° | — | — |
| 2024 | 84° | 65° | 74° | — | — |
| 2023 | 82° | 61° | 71° | — | — |
| 2022 | 84° | 57° | 71° | — | — |
| 2021 | 81° | 60° | 70° | — | — |
| 2020 | 81° | 57° | 69° | — | — |
| 2019 | 90° | 68° | 79° | — | — |
| 2018 | 85° | 60° | 72° | — | — |
| 2017 | 78° | 55° | 67° | — | — |
| 2016 | 92° | 68° | 80° | — | — |
| 2015 | 83° | 67° | 75° | — | — |
| 2014 | 78° | 59° | 69° | — | — |
| 2013 | 85° | 58° | 71° | — | — |
| 2012 | 70° | 57° | 63° | — | — |
| 2011 | 72° | 54° | 63° | — | — |
| 2010 | 60° | 57° | 59° | — | — |
| 2009 | 83° | 61° | 72° | — | — |
| 2008 | 90° | 57° | 73° | — | — |
| 2007 | 75° | 64° | 70° | — | — |
| 2006 | 88° | 57° | 72° | — | — |
| 2005 | 66° | 52° | 59° | — | — |
| 2004coldest | 66° | 48° | 57° | — | — |
| 2003 | 99° | 66° | 82° | — | — |
| 2002 | 66° | 54° | 60° | — | — |
| 2001 | 68° | 55° | 62° | — | — |
| 2000 | 66° | 54° | 60° | — | — |
| 1999warmest | 93° | 73° | 83° | — | — |
| 1998 | 79° | 57° | 68° | — | — |
| 1997 | 74° | 53° | 63° | — | — |
| 1996 | 66° | 55° | 61° | — | — |
| 1995 | 68° | 52° | 60° | — | — |
31 years of data from SIMI VALLEY CALIFORNIA