Last updated: July 2, 2025
Understanding the UV Index in San Francisco, Peru, is crucial for protecting your skin against harmful ultraviolet rays. As residents and visitors navigate the rich cultural landscape of this beautiful city, being aware of the daily UV levels can significantly aid in sunburn prevention and overall skin health. San Francisco's BWh climate often presents unique exposure risks, especially as midday approaches with UV readings peaking at a staggering 11 around noon. By staying informed about the UV Index, you can enjoy the sun safely while embracing all the outdoor experiences San Francisco has to offer.
At 07:00, the UV Index is a mild 1, gradually rising to 2 by 08:00. As the sun climbs higher, the index peaks dramatically at 12:00 with an intense 11, indicating the highest risk of harm from unprotected sun exposure. The intensity starts to wane past 13:00, dropping to 10 and then declining further to 7 by 14:00. The index continues to decrease throughout the afternoon, falling to 4 at 15:00, before tapering off to 2 at 16:00 and 1 by 17:00. Finally, as the sun sets, the UV Index drops to 0 after 18:00, signaling an end to the peak sun exposure of the day. Stay vigilant during those midday hours to protect your skin!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | low | 45 min |
| 09:00 | 4 | moderate | 30 min |
| 10:00 | 7 | high | 25 min |
| 11:00 | 9 | very high | 15 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 10 | very high | 15 min |
| 14:00 | 7 | high | 25 min |
| 15:00 | 4 | moderate | 30 min |
| 16:00 | 2 | low | 45 min |
| 17:00 | 1 | low | 45 min |
| 18:00 | 0 | low | 45 min |
| 19:00 | 0 | low | 45 min |
The UV Index shows significant seasonal variation, with extreme levels persisting from January to April and notable spikes returning in the fall months of September, October, and November. The high-risk months (with a UV Index of 15 or higher) are January through April and November, indicating a consistent risk for sunburn with a burn time as short as 10 minutes during these periods. Even in the summer months of June through August, options remain elevated but shift slightly to very high, allowing a slightly longer exposure of 15 minutes in June before returning to a 10-minute burn time. Visitors and residents should exercise caution, particularly during high UV Index periods, by wearing protective clothing, applying broad-spectrum sunscreen, and seeking shade during peak hours to minimize skin damage and health risks.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Callao UVI | 14 | 14 | 14 | 12 | 10 | 9 | 10 | 11 | 12 | 13 | 14 | 13 |
| Lima UVI | 14 | 14 | 14 | 12 | 10 | 9 | 10 | 11 | 12 | 13 | 14 | 13 |
| Trujillo UVI | 15 | 15 | 15 | 14 | 12 | 11 | 11 | 11 | 13 | 14 | 14 | 14 |
| Chiclayo UVI | 14 | 15 | 15 | 14 | 13 | 11 | 11 | 12 | 15 | 14 | 14 | 13 |
| San Francisco | 15 | 16 | 15 | 14 | 11 | 10 | 11 | 12 | 14 | 15 | 16 | 15 |
| Arequipa UVI | 18 | 17 | 17 | 15 | 12 | 10 | 11 | 13 | 15 | 17 | 18 | 17 |