San Francisco weather in September 2025

Expect 22°C daytime maximum temperatures in the shade with on average 9 hours of sunshine per day in San Francisco in September. Check more long-term weather averages for San Francisco in September before you book your next holiday to California in 2025/2026.

  • 22°C maximum daytime temperature in September in San Francisco22
    22°C max day temperature
  • 9 hours of sunshine per day
  • 2 days with some rainfall in September in San Francisco2
    2 days with some rainfall
  • 13°C minimum night-time temperature in September in San Francisco13
    13°C min night temperature
  • 12 hours of daylight per day in September in San Francisco12
    12 hours of daylight per day
  • No heat & humidity in September in San Francisco0
    No heat & humidity
  • 7 mm monthly rainfall in September in San Francisco7
    7 mm of monthly rainfall
  • UV (maximum) index 7 (High) in September in San Francisco7
    7 (High) UV index
  • 14°C sea temperature in September in San Francisco14
    14°C sea temperature

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The September weather guide for California (San Francisco) shows long term weather averages processed from data supplied by CRU (University of East Anglia), the Met Office & the Netherlands Meteorological Institute. Find out more about our data sources.

Metric (°C / mm)  |  Imperial (°F / inches)

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More about San Francisco

How hot is it in San Francisco in September?

Daytime temperatures usually reach 22°C in San Francisco in September, falling to 13°C at night.

How sunny is it in San Francisco in September?

There are normally 9 hours of bright sunshine each day in San Francisco in September - that's 73% of daylight hours.

How warm is the sea around San Francisco in September?

The average sea temperature around San Francisco in September is 14°C.

Does it ever rain in San Francisco in September?

There are usually 2 days with some rain in San Francisco in September and the average monthly rainfall is 7mm.

San Francisco September sunrise & sunset times

Browse the sunrise and sunset times for San Francisco in September 2025. Select a month to view San Francisco sunrise and sunset times for the next 12 months.

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:40 18:38
Monday, 15th September 2025 05:52 18:17
Tuesday, 30th September 2025 06:05 17:54

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