Simi Valley Weather in September

What's the weather like in Simi Valley (California) in September 2025?

The climate in Simi Valley during September can be summarized as warm and very dry.

September is in the fall / autumn in Simi Valley and is typically the 3rd warmest month of the year. Daytime maximum temperatures average around a comfortable 28°C (82°F), whilst at night 14°C (57°F) is normal.

Simi Valley weather averages (imperial / metric)
Daytime temperature 27.5°C 81.5°F
Nightly temperature 14.1°C 57.4°F
Average temperature 20.8°C 69.4°F
Daily sunshine 10 hrs
Avg rainfall 5 mm 0.2 ins
Rainy days 2 days
Sea temperature 18.6°C 65.5°F
Humidity 68%
Windspeed 11.9kph 7 mph

On average September is the 4th driest month of the year in Simi Valley with around 5mm 0.2 inches of rain making it a very dry time to visit.

On the flip side this corresponds to an average of 10 hours of sunshine per day.

September temperatures in Simi Valley

Simi Valley average temperature in September

September rainfall

Simi Valley average rain in September

September hourly sunshine

Simi Valley average rain in September

The data used in these monthly averages covers a period of over 100 years right up until last year. As such they are a valid prediction of what to expect for the weather in Simi Valley in September 2025.

Other monthly averages

Best places to visit in September

UV index Best time to go?

Beta

Current (hourly) weather 15 day forecast

Simi Valley weather stats

Simi Valley weather statistics
Hottest month: August 28.6°C 83.5°F
Driest month: July 2mm 0.1ins
Sunniest month: August 11.5hrs
Coldest month: January 16.9°C 62.4°F
Wettest month: January 94mm 3.7ins
Map showing location of Simi Valley (34.26945, -118.78148) Simi Valley map pin © Google

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