September · United States
Best time to visit San Francisco in September Weather, crowds & prices
Weather in San Francisco in September
Average temperature 18°C, 8 mm of rain, about 21 days with 6+ hours of sunshine and 73% humidity — based on the five most recent complete years of ERA5 data (2021–2025).
September score
9.6/10
Ranked #4 of 12 months
- Avg temp
- 18°C
- Rainfall
- 8 mm
- Humidity
- 73%
- Days with 6h+ sun
- 21
- Crowd Density
- Moderate Crowds
- Average Expenses
- $$$ · Peak Season Rates ($$$)
September in San Francisco scores 9.6/10 for sightseeing and cultural travel - an above-average month (#4 of 12). Expect around 18°C, 8 mm of rain, and roughly 21 days with 6+ hours of sunshine this month.
Fog-kissed hills, bridges, and bay walks at their most pleasant from April through June.
September ranks 4th of 12 for San Francisco — one of the best windows
Temperatures hover around 18°C (65°F) — the kind of month where neither heat nor cold forces the schedule.
At just 8 mm for the month, rain will not shape your plans; you get about 21 days with 6+ hours of sunshine and 12.2 hours of daylight.
On our climate-comfort scale this is one of the strongest months of the year for San Francisco at 9.6/10 (4th of 12), just behind July at 9.8/10.
Pack layers you can shed by midday plus one warm layer for the evening.
Expect peak pricing, and crowds are moderate.
Frequently asked
- What is the weather like in San Francisco in September?
- In September, San Francisco averages 18°C, 8 mm of rain, and about 21 days with 6+ hours of sunshine. Its climate-comfort score is 9.6/10.
- Is September a good time to visit San Francisco?
- September earns a 9.6/10 climate-comfort score. Use the year-round chart to weigh the weather against your budget and crowd preferences.
- How much does it rain in San Francisco in September?
- Expect about 8 mm of rain in September. Average humidity is 73% and there are about 21 days with 6+ hours of sunshine.
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