Weather in San Francisco in September
September in San Francisco is mild enough that walking is the default. This is a city-break month more than a sea-holiday month.
In United States, this is how San Francisco actually wears September, not how a country centroid would. September is the peak of the warm side of the year in San Francisco. If you wanted the gentlest heat, this is not that month.
- Average temp
- 18°C
14–23°C
- Rainfall
- 2 mm
Not much rain
- Sunshine
- —
- Wind
- 18 km/h
What to expect
Daytime
Mild afternoons in San Francisco are the prize in September. You can eat outside on the good days. You still want something for the breeze.
This is walking weather. Shade is useful, not essential the way it is in the hot months. A long outdoor day is a reasonable plan.
Rain
Rain is not the story in San Francisco in September. Pack for sun. A shower would be news, not a plan.
Do not build the trip around weather windows. Build it around shade if it is hot, and around getting outside if it is not.
Evening
Evenings are cooler. A layer helps after sunset.
What to pack
A layer for cooler evenings
Where to stay in San Francisco
Dates are a starting point for September.
Travel guides for San Francisco
What to read before you book.
Average weather in San Francisco
TemperatureRainfall
Check another month
This is the month you are reading. Change either side to look at another.
FAQs about San Francisco
Climate averages for San Francisco, 1991–2020.
The best time to visit San Francisco is between May and October, the most comfortable stretch of the year on these averages.
September is the hottest month, with an average around 18°C.
December is the wettest month, with about 106 mm of rain.
No. These are 1991–2020 climate normals from Meteostat, not a live forecast. Actual weather in any given week can differ.
