Weather on June 21
Simi Valley, CA
55 Years of Data
Avg High
83°F
Avg Low
58°F
Warmest
2017
88°F avg
Coldest
2003
59°F avg
About This Date
June 21st in Simi Valley, CA typically brings warm summer weather, with average highs around 83°F and lows near 58°F — a 25°F daily swing. Over 30 years of records, the warmest June 21st was in 2017 (88°F average), while the coldest was 2003 (59°F) — a 29°F range across recorded history. This date has historically been dry, with little recorded precipitation. The last decade has been 5.8°F warmer on this date compared to 20-30 years ago.
The last decade has been 5.8°F warmer on this date compared to 20-30 years ago.
Planning for June 21st in Simi Valley, CA? Stay hydrated and seek shade during peak afternoon hours.
Warming Trend
2.3°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 76° | 57° | 66° | — | — |
| 2024 | 88° | 59° | 73° | — | — |
| 2023 | 80° | 57° | 69° | — | — |
| 2022 | 92° | 69° | 80° | — | — |
| 2021 | 91° | 55° | 73° | — | — |
| 2020 | 83° | 56° | 69° | — | — |
| 2019 | 67° | 56° | 61° | — | — |
| 2018 | 87° | 58° | 72° | — | — |
| 2017warmest | 104° | 71° | 88° | — | — |
| 2016 | 95° | 70° | 82° | — | — |
| 2015 | 91° | 64° | 78° | — | — |
| 2014 | 95° | 60° | 78° | — | — |
| 2013 | 86° | 60° | 73° | — | — |
| 2012 | 70° | 55° | 62° | — | — |
| 2011 | 82° | 55° | 69° | — | — |
| 2010 | 73° | 50° | 62° | — | — |
| 2009 | 70° | 55° | 62° | — | — |
| 2008 | 100° | 73° | 87° | — | — |
| 2007 | 82° | 57° | 70° | — | — |
| 2006 | 79° | 54° | 66° | — | — |
| 2005 | 84° | 55° | 70° | — | — |
| 2004 | 72° | 55° | 63° | — | — |
| 2003coldest | 64° | 54° | 59° | — | — |
| 2002 | 70° | 55° | 62° | — | — |
| 2001 | 97° | 67° | 82° | — | — |
| 2000 | 86° | 59° | 73° | — | — |
| 1999 | 77° | 54° | 65° | — | — |
| 1998 | 81° | 53° | 67° | — | — |
| 1997 | 82° | 55° | 69° | — | — |
| 1996 | 78° | 52° | 65° | — | — |
30 years of data from SIMI VALLEY CALIFORNIA