Unlike much of the country, San Francisco is blessed with temperate weather year-round. Winter is cool –– but not frigid –– with temperatures generally in the 30s to 50s. Snow is a rarity. Rain is likely to fall from November through April.
Spring is usually windy and somewhat rainy with moderate warming into the 60s. Summer can also be cool because fog –– our "natural air conditioning" –– forms over the cold Pacific Ocean and is pulled inland by the hotter East Bay temperatures. A 100-degree day occurs occasionally. In fact, Mark Twain is rumored to have written, "The coldest winter I ever spent was a summer in San Francisco."
Most locals look forward to the Fall, when San Francisco is blessed with high temperatures in the 70s to 80s, a warm offshore breeze, and a surprising lack of fog from September through early November.
To see an online update of San Francisco weather, visit SFGate.com/weather.