Water temperature in San Francisco (CA) in September
Is it warm enough to swim in San Francisco in September? Average water temperature in San Francisco in September is 59°F and therefore is not suitable for comfortable swimming. The warmest sea in San Francisco in September is 64.9°F, and the coldest is 55°F. Average high air temperature in San Francisco in September is 70°F, and average low temperature is 55°F. To find out the sea temperature today and in the coming days, go to Current sea temperature in San Francisco
Changes water temperature in San Francisco in September 2025, 2024
To get an accurate forecast for the water temperature in San Francisco for any chosen month, compare two years within a 10 year range using the chart below. In addition to the sea water temperature in San Francisco, the selected years in the table also show the values of the maximum and minimum temperatures on each of the days of September.
You can choose any other years:
| Day | 2025 | 2024 | Min | Max |
|---|---|---|---|---|
| September 1 | 60.4°F | 61°F | 55.4°F | 63.7°F |
| September 2 | 59.7°F | 61°F | 55.4°F | 63.3°F |
| September 3 | 59.7°F | 60.4°F | 55.9°F | 62.8°F |
| September 4 | 59.5°F | 57.7°F | 55.9°F | 62.8°F |
| September 5 | 57.6°F | 55.6°F | 62.8°F | |
| September 6 | 57.7°F | 55.9°F | 62.8°F | |
| September 7 | 57.9°F | 55.9°F | 63°F | |
| September 8 | 57.4°F | 55.9°F | 63°F | |
| September 9 | 57.2°F | 55.6°F | 63°F | |
| September 10 | 59.7°F | 55.6°F | 63.1°F | |
| September 11 | 58.8°F | 55.6°F | 63.3°F | |
| September 12 | 58.1°F | 56.3°F | 63.3°F | |
| September 13 | 57.7°F | 56.7°F | 63.1°F | |
| September 14 | 56.3°F | 56.3°F | 62.8°F | |
| September 15 | 56.1°F | 56.1°F | 63.1°F |
| Day | 2025 | 2024 | Min | Max |
|---|---|---|---|---|
| September 16 | 55.6°F | 55.6°F | 64°F | |
| September 17 | 55.9°F | 55.8°F | 64°F | |
| September 18 | 56.5°F | 55.8°F | 64.2°F | |
| September 19 | 56.1°F | 56.1°F | 64.4°F | |
| September 20 | 57.2°F | 55.8°F | 64.4°F | |
| September 21 | 57.2°F | 55.8°F | 64.6°F | |
| September 22 | 57.6°F | 55°F | 64.9°F | |
| September 23 | 57.7°F | 55.4°F | 64.9°F | |
| September 24 | 59.7°F | 55.8°F | 64.9°F | |
| September 25 | 59.4°F | 55.8°F | 64.8°F | |
| September 26 | 58.3°F | 55.4°F | 64.9°F | |
| September 27 | 58.1°F | 55.4°F | 64°F | |
| September 28 | 58.5°F | 55.4°F | 63.1°F | |
| September 29 | 57.6°F | 55.8°F | 63°F | |
| September 30 | 58.3°F | 55.8°F | 62.6°F |
Average water temperature in San Francisco in September over a decade
| 2015 | 2016 | 2017 | 2018 | 2019 |
| 61.2°F | 58.3°F | 61.5°F | 57.7°F | 59.5°F |
| 2020 | 2021 | 2022 | 2023 | 2024 |
| 59°F | 59°F | 59°F | 60.1°F | 57.9°F |
San Francisco sea state in September
Chart comparing the height of waves in San Francisco in September over the past years. The red line indicates the height of the waves when swimming in the sea is prohibited. To view the current sea conditions, click on the graph.
Weather and climate in San Francisco in September
This data display average monthly climate indicators in San Francisco in September based on our historical weather readings over a period of ten years. In addition to temperature, we include data on the number of rainy and sunny days so you can have all the information about your destination before your trip
- Average HIGH temperature70°F
- Average LOW temperature55°F
- Average rainfall days2 days
- Average rainfall8mm/0.3''
- Average daylight12h
- Average sunshine9h
- Average UV index7
San Francisco water temperature during other months:
You can also view information about water temperature for other months by clicking on the month button below
