Weather on August 18
Simi Valley, CA
55 Years of Data
Avg High
89°F
Avg Low
62°F
Warmest
2020
91°F avg
Coldest
2009
63°F avg
About This Date
August 18th in Simi Valley, CA typically brings warm summer weather, with average highs around 89°F and lows near 62°F — a 27°F daily swing. Over 30 years of records, the warmest August 18th was in 2020 (91°F average), while the coldest was 2009 (63°F) — a 28°F range across recorded history. This date has historically been dry, with little recorded precipitation. The last decade has been 4.2°F warmer on this date compared to 20-30 years ago.
The last decade has been 4.2°F warmer on this date compared to 20-30 years ago.
Planning for August 18th in Simi Valley, CA? Stay hydrated and seek shade during peak afternoon hours.
Warming Trend
1.9°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 90° | 62° | 76° | — | — |
| 2024 | 90° | 60° | 75° | — | — |
| 2023 | 95° | 65° | 80° | — | — |
| 2022 | 97° | 68° | 82° | — | — |
| 2021 | 75° | 62° | 69° | — | — |
| 2020warmest | 110° | 73° | 91° | — | — |
| 2019 | 88° | 57° | 72° | — | — |
| 2018 | 93° | 65° | 79° | — | — |
| 2017 | 91° | 61° | 76° | — | — |
| 2016 | 93° | 63° | 78° | — | — |
| 2015 | 89° | 62° | 76° | — | — |
| 2014 | 98° | 65° | 81° | — | — |
| 2013 | 97° | 64° | 80° | — | — |
| 2012 | 93° | 72° | 82° | — | — |
| 2011 | 86° | 57° | 72° | — | — |
| 2010 | 94° | 69° | 81° | — | — |
| 2009coldest | 75° | 52° | 63° | — | — |
| 2008 | 79° | 59° | 69° | — | — |
| 2007 | 88° | 66° | 77° | — | — |
| 2006 | 79° | 54° | 66° | — | — |
| 2005 | 75° | 54° | 64° | — | — |
| 2004 | 77° | 57° | 67° | — | — |
| 2003 | 86° | 63° | 74° | — | — |
| 2002 | 73° | 59° | 66° | — | — |
| 2001 | 97° | 68° | 82° | — | — |
| 2000 | 95° | 67° | 81° | — | — |
| 1999 | 94° | 66° | 80° | — | — |
| 1998 | 83° | 58° | 70° | — | — |
| 1997 | 94° | 58° | 76° | — | — |
| 1996 | 92° | 60° | 76° | — | — |
30 years of data from SIMI VALLEY CALIFORNIA