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Live forecasts update automatically; written guidance last reviewed 16 June 2026 by the Regional Report weather desk. Data from national met services via Open-Meteo.
Live data from Open-Meteo · updates automatically ·
San Francisco’s famously cool, foggy climate means you can expect mild temperatures year-round, often 10–15°C cooler than inland California — check the live forecast above for the exact conditions today.
What makes San Francisco’s weather so variable?
The city sits on a peninsula surrounded by cool Pacific water, creating a marine layer that produces fog, wind and sharp temperature contrasts between neighbourhoods.
- Fog season — Thick “Karl the Fog” rolls in from June to August, often burning off by midday but returning by evening
- Temperature swings — Summer highs average 18–21°C, but can drop 10°C in a mile as you move from the Mission to the Sunset district
- Winter mildness — December to February sees daytime highs around 13–16°C, with occasional rain and very rare frost
- Wind chill — Strong onshore winds from the Golden Gate make it feel 5–8°C cooler than the thermometer reads, especially near the coast
When should you visit for the best weather?
September and October are typically the warmest, sunniest months, while July and August bring the thickest fog.
- Indian summer (Sep–Oct) — Clear skies, light winds and highs of 22–25°C, the most reliable window for outdoor plans
- Summer fog (Jun–Aug) — Expect overcast mornings, temperatures of 17–20°C and wind; carry layers even on “hot” days
- Winter rain (Nov–Mar) — Around 12–15 rainy days per month, but dry spells between fronts can be crisp and pleasant
Does San Francisco ever get hot?
Very rarely. The cool Pacific current and persistent fog keep summer highs below 25°C most days. A heatwave might push temperatures to 30°C once every few years, but it usually lasts only a day or two before the marine layer returns.
Why is San Francisco so foggy?
Warm inland air rises over California in summer, drawing cold ocean air across the coast. That cold air condenses into fog as it meets warmer air over the city, especially around the Golden Gate. This natural air-conditioning keeps the city cool year-round.
How does San Francisco compare to Los Angeles or Yosemite?
While checking a 10-day forecast is wise for any trip, San Francisco runs 10–15°C cooler than Los Angeles in summer and is far foggier. For bbc weather los angeles expect consistent sunshine and highs of 27–30°C. bbc weather yosemite shows a mountain climate with hot days and cold nights, completely different from the city’s maritime chill.