Shirt-Sleeve Weather In San Francisco

Mark Twain is attributed with the quote, "The coldest winter I ever spent was a summer in San Francisco." As a Giants baseball fan who lives about 30 miles inland on the east side of the Oakland Hills, I can agree. As summer winds down and temperatures drop in the rest of the country, San Francisco is getting its warmest weather of the year. As ocean currents in the northern hemisphere run clockwise, we on the west coast get our ocean water from Alaska. It's cold. This gives San Francisco its famous fog. But an autumn reversal of airflow brings hot air in from California's central valley.

The last several Giants night games were warm enough for people to wear shirtsleeves. I've been to nearly a thousand games in my life and I can count on my fingers the number of night games comfortable enough to wear shorts. The cold fog, high winds, coastal range, Oakland Hills, hot inland weather, and breaks in the hills make the Bay Area the toughest micro-climate area for meteorologists. It's not uncommon in the summer for temps to vary 35 degrees over a half mile in some areas. It might be 105 out here, then we go to a night game with layers of sweaters, jackets and blankets to freeze our fannies off with fog and wind in the low 50's, then return home only to go swimming. It really is true that the 49ers have better weather than the Giants.