Weather on May 21
Simi Valley, CA
55 Years of Data
Avg High
78°F
Avg Low
57°F
Warmest
2006
143°F avg
Coldest
2002
55°F avg
About This Date
May 21st in Simi Valley, CA typically brings pleasant spring weather, with average highs around 78°F and lows near 57°F. Over 30 years of records, the warmest May 21st was in 2006 (143°F average), while the coldest was 2002 (55°F) — a 88°F range across recorded history. This date has historically been dry, with little recorded precipitation. Temperatures on this date have remained relatively stable over the past several decades.
Temperatures on this date have remained relatively stable over the past several decades.
Planning for May 21st in Simi Valley, CA? Great weather for outdoor activities.
Cooling Trend
1.5°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 94° | 66° | 80° | — | — |
| 2024 | 74° | 49° | 61° | — | — |
| 2023 | 84° | 55° | 70° | — | — |
| 2022 | 73° | 51° | 62° | — | — |
| 2021 | 64° | 46° | 55° | — | — |
| 2020 | 87° | 59° | 73° | — | — |
| 2019 | 66° | 48° | 57° | — | — |
| 2018 | 63° | 53° | 58° | — | — |
| 2017 | 95° | 71° | 83° | — | — |
| 2016 | 63° | 48° | 55° | — | — |
| 2015 | 62° | 49° | 55° | — | — |
| 2014 | 69° | 50° | 60° | — | — |
| 2013 | 90° | 57° | 73° | — | — |
| 2012 | 81° | 54° | 67° | — | — |
| 2011 | 70° | 50° | 60° | — | — |
| 2010 | 70° | 51° | 60° | — | — |
| 2009 | 77° | 54° | 65° | — | — |
| 2008 | 73° | 55° | 64° | — | — |
| 2007 | 61° | 55° | 58° | — | — |
| 2006warmest | 145° | 140° | 143° | — | — |
| 2005 | 88° | 63° | 75° | — | — |
| 2004 | 66° | 50° | 58° | — | — |
| 2003 | 91° | 63° | 77° | — | — |
| 2002coldest | 64° | 46° | 55° | — | — |
| 2001 | 83° | 55° | 69° | — | — |
| 2000 | 103° | 62° | 82° | — | — |
| 1999 | 67° | 48° | 57° | — | — |
| 1998 | 67° | 50° | 58° | — | — |
| 1997 | 79° | 55° | 67° | — | — |
| 1996 | 77° | 54° | 65° | — | — |
30 years of data from SIMI VALLEY CALIFORNIA