Riverside Weather in September

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

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

September is in the fall / autumn in Riverside and is typically the 3rd warmest month of the year. Daytime maximum temperatures average around a comfortable 31°C (87°F), whilst at night 15°C (58°F) is normal.

Riverside weather averages (imperial / metric)
Daytime temperature 30.6°C 87°F
Nightly temperature 14.7°C 58.4°F
Average temperature 22.6°C 72.7°F
Daily sunshine 10.2 hrs
Avg rainfall 8 mm 0.3 ins
Rainy days 1 days
Sea temperature 20.4°C 68.8°F
Humidity 62%
Windspeed 13kph 8 mph

On average September is the 4th driest month of the year in Riverside with around 8mm 0.3 inches of rain making it a very dry time to visit.

On the flip side this corresponds to an average of 10.2 hours of sunshine per day.

September temperatures in Riverside

Riverside average temperature in September

September rainfall

Riverside average rain in September

September hourly sunshine

Riverside 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 Riverside 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

Riverside weather stats

Riverside weather statistics
Hottest month: August 32.7°C 90.9°F
Driest month: July 1mm 0ins
Sunniest month: August 11.6hrs
Coldest month: December 18.5°C 65.3°F
Wettest month: January 73mm 2.9ins
Map showing location of Riverside (33.95335, -117.39616) Riverside map pin © Google

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