The hottest month in California is August when the average maximum temperature is 27°, average temperature is 23° and average minimum temperature is 19°.
The coolest month in California is January when the average maximum temperature is 18°, average temperature is 13° and average minimum temperature is 9°.
The longest days in California are in June, with an average of 14.3 hours of daylight per day. December has the shortest days with an average of 10 hours of daylight per day.
The sunniest days in California are in July which has the most hours of sunshine per day with an average of 9.1 hours of sunshine per day, making it a sunny month with few clouds. December has the least sunshine with an average of 5.8 hours of sunshine per day, making it a sunny month that is overcast at times.
The ultraviolet index is the highest in July when it reaches 11.5 and lowest in December when it reaches 3.8.
An ultraviolet index reading above 11 indicates an extreme risk of harm from unprotected sun exposure. Unprotected skin risks burning in less than 10 minutes. Take all precautions because unprotected skin and eyes can burn in minutes. Tanning will be safest before 10am and after 4pm but only with a good application of sun screen. For those with sensitive skin stay in the shade and wear protective clothing, a wide-brimmed hat, and UV-blocking sunglasses. Generously apply broad spectrum SPF 30+ sunscreen every 2 hours, even on cloudy days. Watch out for relections from water that may increase ultraviolet exposure.
The warmest sea water temperatures in California are found in August when they peak at 25° and lowest in March when they dip to 18°.
The sea is best for swimming between June and December when the temperature is above 21° which is comfortable for swimming though some may prefer warmer water.
The wettest month in California is October with 121.3cm of rain and December has the most days of rain with 12.6 days with some rain, a very wet time to visit the beach.
The driest month in California is January with 30.7cm of rain and May has the fewest days of rain with 9.7 days with some rain, a slightly wet time to visit the beach.
The most humid month in California is August with a dew point (an indicator of humidity) of 19° which is somewhat uncomfortable for most people in cities but fine on a beach.
The least humid month in California is January with a dew point of 10° which is very comfortable.
The most windy month in California is April when the average maximum windspeed is 28kmh and the average wind speed is 14kmh.
The least windy month in California is October when the average maximum windspeed is 25kmh and the average wind speed is 11kmh.