San Diego Weather in September

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

The climate in San Diego during September can be summarized as warm, humid and very dry.

September is in the fall / autumn in San Diego and is typically the 3rd warmest month of the year. Daytime maximum temperatures average around a muggy 26°C (79°F), whilst at night 17°C (63°F) is normal.

San Diego weather averages (imperial / metric)
Daytime temperature 26.3°C 79.3°F
Nightly temperature 17°C 62.5°F
Average temperature 21.6°C 70.9°F
Daily sunshine 9.2 hrs
Avg rainfall 4 mm 0.2 ins
Rainy days 1 days
Sea temperature 20.5°C 68.9°F
Humidity 72%
Windspeed 13.3kph 8 mph

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

On the flip side this corresponds to an average of 9.2 hours of sunshine per day.

September temperatures in San Diego

San Diego average temperature in September

September rainfall

San Diego average rain in September

September hourly sunshine

San Diego 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 San Diego 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

San Diego weather stats

San Diego weather statistics
Hottest month: August 26.7°C 80.1°F
Driest month: July 1mm 0ins
Sunniest month: January 8.5hrs
Coldest month: January 18.4°C 65.1°F
Wettest month: January 53mm 2.1ins
Map showing location of San Diego (32.71533, -117.15726) San Diego map pin © Google

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