Clearlake Weather in September

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

September is in the fall / autumn in Clearlake and is typically the 3rd warmest month of the year. Daytime maximum temperatures average around a comfortable 28°C (82°F), whilst at night 10°C (49°F) is normal.

On average September is the 4th driest month of the year in Clearlake with around 13mm 0.5 inches of rain making it a dry time to visit. This rainfall is typically spread over 3 days, although this may vary considerably.

On the flip side this corresponds to an average of 10.7 hours of sunshine per day.

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 Clearlake in September 2025.