Climate averages 1991–2020
Simi Valley weather
in August.
A hot, very dry month: the warmest and the driest of the year.
Long-term climate patterns, not a forecast for a particular trip.
August is a hot month in Simi Valley: daytime highs average 30.7°C and nights cool to about 19.3°C. By daytime temperature it is the warmest month of the year.
Rain is very rare: less than 1 mm falls in a typical August (the driest month of the year). Daylight, from sunrise to sunset, lasts about 13 h 26 min on an average August day.
The nearest other city in this atlas is Thousand Oaks (12 km away). In August its highs average 29.5°C, 1.1°C cooler than Simi Valley, with almost no rain (under 1 mm).
Among the 498 cities listed in the United States, Simi Valley ranks joint 186th of 498 for the warmest August highs and joint 2nd of 498 for the driest August (rainfall, lowest first). The mean August high of those 498 cities is 29.9°C; Simi Valley is 0.8°C warmer than that mean.
From August to September, average highs fall by 1.2°C to 29.5°C, and monthly rainfall rises from under 1 mm to 3.9 mm.
The annual picture
August in context
Monthly rainfall
Average total · mmAverages from hourly ERA5 reanalysis data. Actual weather varies from year to year. How these numbers are calculated
Every month, side by side
Simi Valley climate table
| Month | Average highHigh / low | Average low | Rainfall mm/month | Rain days ≥1 mm/day | Daylight hours/dayDaylight h/day |
|---|---|---|---|---|---|
| January | 17.7°C6.0°C | 6.0°C | 91 | 5.6 | 10.110 h |
| February | 17.8°C6.4°C | 6.4°C | 98 | 6.4 | 10.911 h |
| March | 19.5°C7.9°C | 7.9°C | 66 | 5.6 | 11.912 h |
| April | 21.7°C9.7°C | 9.7°C | 22 | 2.9 | 13.013 h |
| May | 23.9°C12.7°C | 12.7°C | 12 | 1.8 | 13.914 h |
| June | 26.8°C15.6°C | 15.6°C | 2.0 | 0.5 | 14.414 h |
| July | 29.6°C18.7°C | 18.7°C | 3.1 | 0.5 | 14.214 h |
| August, selected | 30.7°C19.3°C | 19.3°C | 0.3 | 0.1 | 13.413 h |
| September | 29.5°C17.6°C | 17.6°C | 3.9 | 0.6 | 12.412 h |
| October | 25.8°C13.7°C | 13.7°C | 20 | 2.1 | 11.411 h |
| November | 21.5°C9.2°C | 9.2°C | 21 | 2.6 | 10.410 h |
| December | 17.4°C5.9°C | 5.9°C | 58 | 4.8 | 9.910 h |
Rainfall is the average of the 30 separate monthly totals. A rain day is a local calendar day with at least 1 mm of precipitation. Daylight is the calculated sunrise-to-sunset length, not measured sunshine.
Compare places
August in nearby cities
- Thousand Oaks in AugustUnited States · 12 kmHigh 29.5°C · Low 19.1°C · 0.3 mm rain
- Valencia, United States in AugustUnited States · 25 kmHigh 32.6°C · Low 19.6°C · 0.7 mm rain
- Santa Clarita in AugustUnited States · 26 kmHigh 32.6°C · Low 19.6°C · 0.7 mm rain
- Oxnard in AugustUnited States · 37 kmHigh 24.8°C · Low 17.8°C · 0.3 mm rain
- Burbank in AugustUnited States · 45 kmHigh 33.3°C · Low 19.6°C · 0.9 mm rain
- Ventura in AugustUnited States · 47 kmHigh 26.6°C · Low 18.7°C · 0.3 mm rain
- Glendale (California), United States in AugustUnited States · 50 kmHigh 31.7°C · Low 18.2°C · 0.9 mm rain
- Inglewood in AugustUnited States · 52 kmHigh 30.0°C · Low 18.6°C · 0.3 mm rain
Read the numbers correctly
Climate, not a promise.
These patterns help compare months. They cannot tell you the weather on a specific day of your trip.
Sources, method and limitsHow these numbers are made (what the highs, lows and rain days mean, the sources and the model cell used for Simi Valley) is explained once on the Simi Valley year overview and on the Sources, method and limits page.
Thousand Oaks lies in the same rainfall cell, so its rainfall figures are identical to these; temperatures differ because they come from smaller 0.1° cells.