San Francisco Weather in September
September in San Francisco brings high temperatures, with daytime highs of 23°C (73°F) and nights around 13°C (55°F). Only 3.4 mm (0.1 in) of rainfall is typical, making it a largely dry month.
Rainfall in San Francisco in September
Rain is expected on roughly a single day, totalling around 3.4 mm (0.1 in) for the month. Any rain that does arrive is likely to be light drizzle rather than a proper shower.
Temperature in San Francisco in September
The perfect temperature in San Francisco in September makes it a solid month to visit, with 23°C (73°F) during the day and 13°C (55°F) at night. Conditions stay fairly consistent through the month, making it easier to plan what to wear. Nights drop to around 13°C (55°F), which is noticeably cooler than the daytime. A light jacket for the evening is a sensible addition, and the cool nights tend to make sleeping comfortable. On average, it has the peak temperatures of the year.
Sunshine in San Francisco in September
Expect a lot of sunshine this month, with about 270 hours of sun. These sunny conditions add to the overall experience.
Wind Speed in San Francisco in September
Average wind conditions reach 5 m/s (10 knots) in September. This creates lively weather with fresh winds that make small trees sway noticeably. Remember this is an average: some days are less windy while others have particularly active windy conditions.
Average water temperature in September
The water is 14°C (57°F) this month — cool enough to feel refreshing on a warm day, but cold enough that most people won't stay in for long without a wetsuit.If you favor pleasant temperatures and minimal rainfall, September is one of the best months to visit San Francisco.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our San Francisco's climate page.
San Francisco Temperature in September
Min Temperature
13°C (55°F)
Max Temperature
23°C (73°F)
Water Temperature
14°C (57°F)
Chance of Rain
3%
Precipitation
3.4 mm (0.1 in)
Rainy days
a single day
Humidity
73%
Windspeed
5 m/s (10 knots)
Sunshine
270 hours
Percentage Sunshine
73%
Daily Historical Temperatures
50-year average (1976-2025)
Based on our historical records, temperatures in San Francisco typically stay consistent throughout September, with daily highs averaging around 23°C (73°F). Nights are cool, with lows around 14°C (57°F).
Average temperatures in September
Daily Historical Precipitation
50-year average (1976-2025)
Average daily rainfall for each day of the month based on long-term records.
Average precipitation in September
Historical weather for San Francisco in September
Browse day-by-day weather records for San Francisco spanning 51 years. Select any month and year to see actual temperatures, rainfall, and conditions recorded on each day.
San Francisco historical weather extremes in September
Based on 49 years of weather observations in San Francisco between 1976 and 2025, these are the recorded extremes.
- The hottest September day on record in San Francisco reached 39°C (102°F) (September 6, 2020).
- On September 16, 2001, San Francisco saw its coldest September day with temperatures maxing out at 15°C (59°F).
- The coldest night in September in San Francisco was on September 22, 1981, with a minimum of 9°C (48°F).
Best Places in the United States of America in September
Find out more about the weather in the United States of America and which places have the best travel conditions in this month. See all of the United States of America in September →
perfect weather
pleasant
tolerable
unpleasant
poor
What to Wear in San Francisco in September
For San Francisco in September, you'll want flexible clothing. It's wise to pack cotton shirts, comfortable shorts, and a pair of jeans for cooler evenings. A light sweater or jacket is useful for air-conditioned spaces (like buses) or unexpected cool moments. Almost no rain is expected, so no need to bring rain gear. Expect water temperatures of around 14°C (57°F), which is definitely too cold for comfortable swimming. Your luggage space is better used for other items. And with plenty of sunshine hours, don’t forget sunglasses, sunscreen, and maybe a sun hat.What To Do in San Francisco in September
We rated the following activities from 1 (least suitable) to 10 (best) to do.
Check the conditions for any month of the year.
For a detailed overview over the year and the best time to visit the United States of America, check out our San Francisco's climate page.
Temperature Rainfall Sunshine Humidity Wind Speed Water Temp
See the full San Francisco climate overview or explore weather in the United States of America.
