Clearlake Weather in December

What's the weather like in Clearlake (California) in December 2025?

The climate in Clearlake during December can be summarized as cool and wet.

December is in the winter in Clearlake and is typically the 2nd coldest month of the year. Daytime maximum temperatures average around a cool 12°C (53°F), whilst at night 1°C (34°F) is normal.

Clearlake weather averages (imperial / metric)
Daytime temperature 11.7°C 53.1°F
Nightly temperature 1.3°C 34.3°F
Average temperature 6.5°C 43.7°F
Daily sunshine 5.6 hrs
Avg rainfall 171 mm 6.7 ins
Rainy days 11 days
Sea temperature 12.6°C 54.6°F
Humidity 81%
Windspeed 11.5kph 7 mph

On average December is the 2nd wettest month of the year in Clearlake with around 171mm 6.7 inches of rain making it a wet time to visit. This rainfall is typically spread over 11 days, although this may vary considerably.

On the flip side this corresponds to an average of 5.6 hours of sunshine per day.

December temperatures in Clearlake

Clearlake average temperature in December

December rainfall

Clearlake average rain in December

December hourly sunshine

Clearlake average rain in December

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 December 2025.