San Francisco in May: What to Expect

San Francisco in May has a reputation for being foggy, and that reputation is at least partly earned. May is the start of the fog season, driven by the temperature differential between the cool Pacific and the warm Central Valley. It's not a reason not to go, but it's worth understanding before you book expecting California sunshine every day.

Weather

Temperatures in May range from 12°C to 18°C, which is milder than most people expect from California. The fog, known locally as Karl, often sits over the western neighbourhoods and can persist into the afternoon. The eastern parts of the city, downtown, the Mission, and Castro, tend to get more sunshine than the Outer Sunset or the Richmond. Pack layers. You will need a jacket, potentially a heavier one than you'd expect for a late May trip.

Crowds and Prices

May is below the summer peak but San Francisco is expensive year-round. Hotel prices are high, food and transport are costly, and tourist sites like Alcatraz and the Golden Gate Bridge fill up. Alcatraz ferries book out days to weeks in advance: reserve before you travel. Memorial Day weekend at the end of May brings price spikes and crowds.

What's On

Bay to Breakers, one of the world's most eccentric running races, takes place in mid-May. Around 50,000 participants run from the Embarcadero to Ocean Beach in fancy dress, and the city embraces the chaos. It's a San Francisco experience unlike anything else.

The Carnaval San Francisco festival in the Mission District takes place in late May and celebrates Latin American culture with music, dancing, and one of the city's biggest street parades.

One Thing to Watch

Alcatraz ferry tickets sell out considerably in advance. This is not an exaggeration and it's the mistake most visitors make. The National Park Service ferry is the only authorised way to reach the island, and it operates on timed departures. For May visits, check availability as soon as you have confirmed travel dates and book immediately. The audio tour on the island is excellent. Showing up at Pier 33 without a ticket on a May morning is a wasted journey.

Our San Francisco travel guide covers the city neighbourhood by neighbourhood and keeps you from losing a morning to a fixable planning mistake.