What September feels like in San Francisco
Early autumn arrives in San Francisco with September. The middle of the day is pleasantly mild. After sunset it cools off noticeably — nights stay mild. Humidity is on the high side, but mild temperatures keep it comfortable.
Rain in San Francisco in September
Rain is rare in September — most weeks pass without a wet day. Rainfall per wet day is small, about 3.1 mm (0.1 in), so showers tend to pass quickly. That is lighter than the city's yearly norm of about 9.6 mm per rainy day.
Daylight and sunshine in September
On 15 September the sun rises at about 6:50 am and sets around 7:20 pm local time, giving 12 h 29 min of daylight. Evenings are drawing in — 1 h 11 min less daylight than mid-August. Measured sunshine covers about 92% of the daylight — skies are mostly clear.
How September compares to the rest of the year
September is the warmest month of the year in San Francisco. Compared with August, afternoons are 1°C (1.8°F) warmer, with 3 mm more rain. From here temperatures start to ease, beginning in October. The next month's average high: 20.6°C (69.1°F).
Who September suits
- Sightseeing: a good fit — comfortable enough to explore on foot all day.
- Parks & outdoor: a good fit — pleasant for gardens, parks and riversides.
- Beach: a good fit — warm and mostly dry on the coast.
Tips for visiting San Francisco in September
Versatile Layers
Days are noticeably warmer than nights — layers you can add or remove.
Sunglasses
Bright days make sunglasses worth packing.
Quick questions
How warm is San Francisco in September?
Expect around 21.8°C (71.2°F) in the afternoon and 13.7°C (56.7°F) at night, which most visitors would call mild.
Does it rain a lot in San Francisco in September?
Hardly — only about 1 rainy days and 3 mm for the whole month.
What should I wear in San Francisco in September?
The numbers point to versatile layers and sunglasses. Bring something extra for the cooler evenings.
Is September or October better for visiting San Francisco?
September, narrowly: it ranks #4 of 12 among San Francisco's months, against #6 for the other. October is cooler and has more rainy days.