Weather on May 18
Simi Valley, CA
55 Years of Data
Avg High
78°F
Avg Low
56°F
Warmest
2006
142°F avg
Coldest
2011
55°F avg
About This Date
May 18th in Simi Valley, CA typically brings pleasant spring weather, with average highs around 78°F and lows near 56°F. Over 30 years of records, the warmest May 18th was in 2006 (142°F average), while the coldest was 2011 (55°F) — a 87°F range across recorded history. This date has historically been dry, with little recorded precipitation. The last decade has been 1.9°F cooler on this date compared to 20-30 years ago.
The last decade has been 1.9°F cooler on this date compared to 20-30 years ago.
Planning for May 18th in Simi Valley, CA? Great weather for outdoor activities.
Cooling Trend
2.9°F per decade on this date
| Year | High | Low | Avg | Precip | Snow |
|---|---|---|---|---|---|
| 2025 | 76° | 48° | 62° | — | — |
| 2024 | 74° | 51° | 62° | — | — |
| 2023 | 80° | 53° | 67° | — | — |
| 2022 | 81° | 52° | 66° | — | — |
| 2021 | 80° | 50° | 65° | — | — |
| 2020 | 70° | 49° | 59° | — | — |
| 2019 | 72° | 47° | 59° | — | — |
| 2018 | 73° | 50° | 62° | — | — |
| 2017 | 81° | 49° | 65° | — | — |
| 2016 | 81° | 54° | 67° | — | — |
| 2015 | 69° | 50° | 60° | — | — |
| 2014 | 78° | 54° | 66° | — | — |
| 2013 | 80° | 52° | 66° | — | — |
| 2012 | 70° | 52° | 61° | — | — |
| 2011coldest | 63° | 48° | 55° | — | — |
| 2010 | 65° | 52° | 58° | — | — |
| 2009 | 77° | 54° | 65° | — | — |
| 2008 | 91° | 72° | 81° | — | — |
| 2007 | 70° | 50° | 60° | — | — |
| 2006warmest | 145° | 138° | 142° | — | — |
| 2005 | 72° | 54° | 63° | — | — |
| 2004 | 68° | 55° | 62° | — | — |
| 2003 | 70° | 54° | 62° | — | — |
| 2002 | 70° | 50° | 60° | — | — |
| 2001 | 74° | 54° | 64° | — | — |
| 2000 | 87° | 56° | 71° | — | — |
| 1999 | 80° | 55° | 68° | — | — |
| 1998 | 79° | 53° | 66° | — | — |
| 1997 | 80° | 59° | 70° | — | — |
| 1996 | 81° | 54° | 67° | — | — |
30 years of data from SIMI VALLEY CALIFORNIA