Verdict: Excellent month
San Francisco Weather in September
September hits the sweet spot in San Francisco — highs around 20°C (68°F), ideal for a full day on foot. Rain is a non-issue, with only ~1 wet day in an average year. Overall, September is one of the best months of the year to be in San Francisco.
Average high
20°C / 68°F
Average low
14°C / 57°F
Rain days
~1
Precipitation
4 mm
What to pack for San Francisco in September
- Layers — t-shirts under a light jacket or sweater
- Comfortable walking shoes — every guide on this site assumes you'll use them
September against the rest of the year
Warmest in San Francisco: Oct (21°C / 70°F) · Coolest: Dec (13°C / 55°F) · Wettest: Dec (~12 rain days)
14°
8°
Jan
15°
8°
Feb
14°
9°
Mar
15°
10°
Apr
17°
11°
May
19°
13°
Jun
19°
13°
Jul
20°
14°
Aug
20°
14°
Sep
21°
13°
Oct
16°
10°
Nov
13°
8°
Dec
Daily highs / lows in °C · bars show rain days per month · ERA5 climate normals (2020–2024)