San Francisco Weather: Fog, Microclimates and What to Wear

The most useful thing anyone can tell you about San Francisco weather is that the seasons are shifted. Summer is the cold, gray season. Fall is the warm one. Everything else follows from that.

The real seasons

Summer, June to August, is fog season. Hot air in the Central Valley pulls cool ocean air in through the Golden Gate, and the fog sits over the western half of the city for days at a time. Mornings and evenings are in the fifties. Locals call it Fogust and complain about it every year.

September and October are the warm, clear months and the best time to visit or to plan a beach day. September is the single warmest month of the year here, with average highs around seventy.

November through March is the rainy season, peaking in January and February. Highs stay in the upper fifties, so it is mild rather than cold, but it is genuinely wet: the city averages roughly twenty to twenty-two inches a year, and most of it falls in these months.

April and May are the transition, often lovely, with the fog building by late May.

Average temperatures by month

These are the National Weather Service normals for downtown San Francisco, in Fahrenheit, high and low:

January 57/46 · February 60/48 · March 62/49 · April 63/49 · May 64/51 · June 66/53 · July 67/54 · August 68/55 · September 70/55 · October 69/54 · November 63/50 · December 57/46

Notice the range. There is thirteen degrees between the coldest month and the warmest, all year. San Francisco does not really have a summer or a winter; it has a gray season and a clear one.

Microclimates are not a myth

On the same July afternoon, the Mission, Noe Valley, Potrero Hill and Bayview can be sunny and in the seventies while the Outer Sunset and Outer Richmond sit under fog in the upper fifties. Twin Peaks acts as a wall. Downtown and the waterfront fall in between and can flip in an hour.

The practical version: if your day is fogged out on the west side, drive east. If you want fog, drive west. Both take twenty minutes.

Wind

Afternoon wind is the other thing visitors underestimate. Ocean air accelerates through the Golden Gate as the inland valleys heat up, so wind is strongest in the mid-to-late afternoon and strongest overall from May through August. Crissy Field, Ocean Beach and every hilltop are noticeably colder than the forecast suggests. Mornings are calmer, which is why we put beach and bike plans early in the day.

What to pack for kids

Summer: long sleeves, a fleece and a windbreaker, even in July, plus long pants for the coast and closed-toe shoes. A sun hat for the east side and a beanie for the west side is not a joke.

September and October: t-shirts by day, one warm layer for the evening. This is the stretch when the beach actually works.

Winter: a rain jacket with a hood, waterproof shoes and warm layers. Umbrellas fail in the wind; hoods do not.

Spring: layers again, with sunscreen. Fog does not stop sunburn.

Temperature normals from the National Weather Service; rainfall figures from Golden Gate Weather Services.

Prices and hours were checked in September 2026 and can change, so confirm before you go.