San Luis Obispo Weather in September

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

The climate in San Luis Obispo during September can be summarized as warm and very dry.

September is in the fall / autumn in San Luis Obispo and is typically the 3rd warmest month of the year. Daytime maximum temperatures average around 26°C (78°F), whilst at night 11°C (52°F) is normal.

San Luis Obispo weather averages (imperial / metric)
Daytime temperature	25.5°C 77.8°F
Nightly temperature	11.2°C 52.1°F
Average temperature	18.3°C 64.9°F
Daily sunshine	10 hrs
Avg rainfall	10 mm 0.4 ins
Rainy days	2 days
Sea temperature	17°C 62.6°F
Humidity	74%
Windspeed	10.8kph 7 mph

On average September is the 5th driest month of the year in San Luis Obispo with around 10mm 0.4 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 San Luis Obispo

San Luis Obispo average temperature in September

September rainfall

San Luis Obispo average rain in September

September hourly sunshine

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 Luis Obispo 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 Luis Obispo weather stats

San Luis Obispo weather statistics
Hottest month:	August	25.8°C 78.4°F
Driest month:	June	2mm 0.1ins
Sunniest month:	April	11hrs
Coldest month:	January	15.7°C 60.3°F
Wettest month:	January	100mm 3.9ins

Map showing location of San Luis Obispo (35.28275, -120.65962)