San Francisco, CA Weather Forecast & Climate Guide
San Francisco has a Mediterranean climate strongly influenced by cold ocean currents. The city is famous for its fog and cool summers, with distinct microclimates across neighborhoods.
Climate type: Mediterranean / cool-summer subtropical (Köppen Csb)
San Francisco Climate Overview
Temperatures are remarkably stable year-round, typically between 50-70°F (10-21°C). Summer can be foggy and cool, while fall offers the warmest weather. Annual rainfall is about 23 inches.
The famous fog rolls in through the Golden Gate, cooling western neighborhoods while eastern areas stay warm. Karl the Fog is most common in summer mornings.
San Francisco Weather by Season
spring
Spring is mild, often sunnier than summer along the coast. Highs in the 60s°F, cool nights, and hills turning green from winter rains before drying out.
summer
San Francisco summers defy expectations — cold, foggy, and windy along the coast with highs barely reaching 65°F. "Karl the Fog" dominates mornings and evenings, especially in the Sunset and Richmond districts.
fall
Fall is San Francisco's secret best season. September and October bring the warmest, sunniest, fog-free weather of the year with highs in the 70s°F.
winter
Winters are mild and rainy with highs in the upper 50s°F and lows in the 40s°F. Most of the city's 23 inches of annual rain falls between December and March during atmospheric river events.
San Francisco Average Monthly Temperatures
| Month | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| High °F | 58° | 61° | 63° | 65° | 66° | 68° | 68° | 69° | 72° | 70° | 63° | 58° |
| Low °F | 46° | 48° | 49° | 50° | 52° | 54° | 55° | 56° | 55° | 54° | 50° | 46° |
Best Time to Visit San Francisco
September and October. Warmest temperatures, minimal fog, low rain, and uncrowded attractions. Locals call this the city's "real summer." March-May is also pleasant and less foggy than June-August.
Severe Weather Risks
- Coastal fog
- Atmospheric rivers
- Wildfire smoke
- King tides
- Wind events
Weather Facts About San Francisco
- >San Francisco's July average high is 67°F — cooler than New York, Chicago, or even Seattle.
- >Microclimates mean neighborhoods 5 miles apart can have 15°F temperature differences on the same afternoon.
- >The coldest temperature ever recorded in SF is 27°F — the city has never officially seen snow stick downtown.
San Francisco Weather FAQ
Why is San Francisco cold in summer?
Cold Pacific water offshore creates a marine layer of fog that's sucked in through the Golden Gate by rising warm air in the Central Valley. The result: July and August are often the coldest months of the year in SF.
When is the best time to visit San Francisco?
September and October. The fog retreats, skies clear, temperatures push into the 70s°F, and locals finally wear short sleeves. This is the city's true summer.
Does it rain much in San Francisco?
About 23 inches per year, almost entirely between November and April. Summer is essentially dry, and individual atmospheric river storms can dump 2-4 inches in a day.
What is "Karl the Fog"?
Locals named the persistent coastal fog "Karl." It rolls in through the Golden Gate most afternoons in summer, blanketing the western neighborhoods while eastern areas stay sunny. Karl even has his own Twitter account.