Best Time to Visit San Francisco

Short answer: September and October. They're the warmest, clearest weeks of the year, the fog mostly stays offshore, and the summer crowds have thinned out. Locals call it their real summer.

That surprises a lot of visitors, who arrive in July expecting California sunshine and find 15°C (about 60°F), grey skies and a cold wind off the ocean. The line "the coldest winter I ever spent was a summer in San Francisco" is usually credited to Mark Twain, though there's no evidence he said it. It's accurate either way. The reason is geography: as the inland valleys heat up, they pull cold, damp air in from the Pacific through the Golden Gate. Fifty kilometres inland, in Napa, it can be 35°C on the same afternoon.

Season by season

• Spring (March to May): green hills, wildflowers on the coastal trails, windy afternoons and some late rain. A pleasant, less crowded time.
• Summer (June to August): the busiest and most expensive season. Mornings and evenings are often foggy, especially near the ocean and the bridge. The Mission and the East Bay stay sunnier.
• Autumn (September to October): warm days, clear views of the bridge, the best time for Alcatraz and the coast. November turns cooler and the first rains arrive.
• Winter (December to February): mild, rarely below 8°C in the day, with most of the year's rain in storms that pass through in a few days. Hotels are cheaper, and Dungeness crab season starts in November.

Events that move hotel prices

Big conferences at the Moscone Center, especially Dreamforce, the huge tech event usually held in the autumn, can fill downtown hotels. Pride falls on the last weekend of June. Outside Lands, a music festival in Golden Gate Park, takes over a weekend in August. Fleet Week in early October brings the Blue Angels flying over the bay, and Hardly Strictly Bluegrass, a free festival in the park, runs around the same time. The Chinese New Year parade, in February or March, is one of the largest outside Asia.

Alcatraz sells out furthest ahead from late spring to early autumn, so book as soon as your dates are fixed. In any month, pack for fog: our what to wear guide explains the layers.