Portola Valley Weather in January

The climate in Portola Valley during January can be summarized as cool and wet.

January is in the winter in Portola Valley and is typically the coldest month of the year. Daytime maximum temperatures average around a cool 14°C (56°F), whilst at night 4°C (40°F) is normal.

On average January is the wettest month of the year in Portola Valley with around 133mm 5.2 inches of rain making it a wet 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 6.3 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 Portola Valley in January 2025.