average weather in san diego ca
San Diego: Annual Weather Averages. August is the hottest month in San Diego with an average temperature of 23Â°C (73Â°F) and the coldest is January at 14Â°C (57Â°F) with the most daily sunshine hours at 10 in July. The wettest month is February with an average of 53mm of rain. The best month to swim in the sea is in August when the average sea temperature is 20Â°C (68Â°F).