San Diego weather in September 2025

Q: 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.

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 70% of daylight hours.

Q: How warm is the sea around San Diego in September?

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

Q: 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.

Q: What is the chance of a cyclone 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.

Expect 79°F 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.

79
79°F max day temperature
9
9 hours of sunshine per day
1
1 day with some rainfall
63
63°F min night temperature
12
12 hours of daylight per day
L
Low heat & humidity
0.2
0.2 inches of monthly rainfall
8
8 (Very High) UV index
68
68°F 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) | Imperial (°F)

More about California

How hot is it in San Diego in September?

Daytime temperatures usually reach 79°F in San Diego in September with low heat and humidity, falling to 63°F 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 68°F.

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 0.2 inches.

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.

Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec

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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California - quick facts
Flight time^✝	11 hours
Time difference	UK -8 hours
Language(s)	English
Currency	US Dollar
Electricity	A + B plug (120V)
Driving side	Right
Visa^✝	Yes
Why visit?	Beaches Culture Nature Nightlife
Tourist info	Visit California