Castro Valley Weather in December

The climate in Castro Valley during December can be summarized as cool and a little damp.

December is in the winter in Castro Valley and is typically the 2nd coldest month of the year. Daytime maximum temperatures average around a cool 13°C (56°F), whilst at night 5°C (41°F) is normal.

On average December is the 2nd wettest month of the year in Castro Valley with around 82mm 3.2 inches of rain making it a a little damp time to visit. This rainfall is typically spread over 9 days, although this may vary considerably.

On the flip side this corresponds to an average of 5.6 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 Castro Valley in December 2024.