San Diego weather in September 2025

Expect 26°C daytime maximum temperatures in the shade with on average 9 hours of sunshine per day in San Diego in September. Check more long-term weather averages for San Diego in September before you book your next holiday to California in 2025/2026.

  • 26°C maximum daytime temperature in September in San Diego26
    26°C max day temperature
  • 9 hours of sunshine per day
  • 1 day with some rainfall in September in San Diego1
    1 day with some rainfall
  • 17°C minimum night-time temperature in September in San Diego17
    17°C min night temperature
  • 12 hours of daylight per day in September in San Diego12
    12 hours of daylight per day
  • Low heat & humidity in September in San DiegoL
    Low heat & humidity
  • 4 mm monthly rainfall in September in San Diego4
    4 mm of monthly rainfall
  • UV (maximum) index 8 (Very High) in September in San Diego8
    8 (Very High) UV index
  • 20°C sea temperature in September in San Diego20
    20°C sea temperature

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The September weather guide for California (San Diego) 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 California

How hot is it in San Diego in September?

Daytime temperatures usually reach 26°C in San Diego in September with low heat and humidity, falling to 17°C at night.

How sunny is it in San Diego in September?

There are normally 9 hours of bright sunshine each day in San Diego in September - that's 70% of daylight hours.

How warm is the sea around San Diego in September?

The average sea temperature around San Diego in September is 20°C.

Does it ever rain in San Diego in September?

There is usually 1 day with some rain in San Diego in September and the average monthly rainfall is 4mm.

What is the chance of a hurricane in San Diego in September?

On average less than 1 day in September in San Diego is likely to be affected by the passage of one or more tropical storms.

San Diego September sunrise & sunset times

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

JanFebMarAprMayJunJulAugSepOctNovDec

Date Sunrise times Sunset times
Monday, 1st September 2025 05:24 18:13
Monday, 15th September 2025 05:33 17:54
Tuesday, 30th September 2025 05:42 17:34

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