Half Moon Bay Weather in December

What's the weather like in Half Moon Bay (California) in December 2025?

The climate in Half Moon Bay during December can be summarized as cool and damp.

December is in the winter in Half Moon Bay and is typically the 2nd coldest month of the year. Daytime maximum temperatures average around a cool 14°C (57°F), whilst at night 5°C (41°F) is normal.

Half Moon Bay weather averages (imperial / metric)
Daytime temperature 13.7°C 56.6°F
Nightly temperature 5.2°C 41.3°F
Average temperature 9.4°C 48.9°F
Daily sunshine 5.6 hrs
Avg rainfall 114 mm 4.5 ins
Rainy days 10 days
Sea temperature 12.7°C 54.9°F
Humidity 79%
Windspeed 12.6kph 8 mph

On average December is the 2nd wettest month of the year in Half Moon Bay with around 114mm 4.5 inches of rain making it a damp time to visit. This rainfall is typically spread over 10 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 Half Moon Bay

Half Moon Bay average temperature in December

December rainfall

Half Moon Bay average rain in December

December hourly sunshine

Half Moon Bay 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 Half Moon Bay in December 2025.

Other monthly averages

Best places to visit in December

UV index Best time to go?

Beta

Current (hourly) weather 15 day forecast

Half Moon Bay weather stats

Half Moon Bay weather statistics
Hottest month: September 22.5°C 72.5°F
Driest month: July 2mm 0.1ins
Sunniest month: April 11hrs
Coldest month: January 13.4°C 56.1°F
Wettest month: January 146mm 5.7ins
Map showing location of Half Moon Bay (37.46355, -122.42859) Half Moon Bay map pin © Google

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