San Diego weather in September 2026

Q: How hot is it in San Diego in September?

Daytime temperatures usually reach 28°C in San Diego in September with moderate heat and humidity, falling to 17°C at night.

Q: 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 75% of daylight hours.

Q: Does it ever rain in San Diego in September?

There are usually 2 days with some rain in San Diego in September and the average monthly rainfall is 9mm.

Expect daytime maximum temperatures of 26°C in San Diego, California in September based on long-term weather averages. There are 9 hours of sunshine per day on average.

26
26°C max day temperature
9
9 hours of sunshine per day
1
1 day with some rainfall
17
17°C min night temperature
12
12 hours of daylight per day
L
Low heat & humidity
4
4 mm of monthly rainfall
8
8 (Very High) UV index
20
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)

More about California

How hot is it in San Diego in September?

Daytime temperatures usually reach 28°C in San Diego in September with moderate 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 75% of daylight hours.

Does it ever rain in San Diego in September?

There are usually 2 days with some rain in San Diego in September and the average monthly rainfall is 9mm.

San Diego September sunrise & sunset times

Browse the sunrise and sunset times for San Diego in September 2026. Select a month to view San Diego sunrise and sunset times for the next 12 months.

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