UV index in San Francisco
California, United States · typical UV by month
Today's UV in San Francisco
The hourly forecast and the lower-UV times for what you do outside. Free, no account needed.
The year at a glance
- UV in San Francisco is highest in June, when a typical day peaks around 8 (Very high).
- On a typical June day, UV is 3 or more from about 10am to 6pm, about 8 hours.
- The typical midday UV reaches 3 or more from February to November, when public-health guidance recommends sun protection.
- UV usually stays under 3 in December and January.
- Clouds take the most off in July: a typical peak of 8, against 10 under a clear sky. On a clear day, expect the higher number.
Typical UV by month
The highest UV index of a typical day, with clouds and under a clear sky, and the hours UV is usually 3 or more, from 2023 to 2025.
| Month | Typical peak | Clear sky | UV 3 or more |
|---|---|---|---|
| JanJanuary | 2 Low | 2 | Rarely |
| FebFebruary | 3 Moderate | 3 | 11am-2pm |
| MarMarch | 4 Moderate | 5 | 11am-4pm |
| AprApril | 6 High | 7 | 10am-5pm |
| MayMay | 8 Very high | 8 | 10am-5pm |
| JunJune | 8 Very high | 9 | 10am-6pm |
| JulJuly | 8 Very high | 10 | 10am-6pm |
| AugAugust | 7 High | 9 | 10am-5pm |
| SepSeptember | 6 High | 7 | 10am-5pm |
| OctOctober | 5 Moderate | 5 | 11am-4pm |
| NovNovember | 3 Moderate | 3 | Rarely |
| DecDecember | 2 Low | 2 | Rarely |
About these numbers
Averages of every day from 2023 to 2025 in the global atmospheric composition model of the Copernicus Atmosphere Monitoring Service, served by the Open-Meteo Air Quality API (CC BY 4.0), for the city center, in local time. They describe a typical day, not any one day: the UV on a given day can be higher or lower, so check the forecast before you go. Solara is a planning aid, not medical advice.