Last updated: May 3, 2025
Understanding the UV Index in Yosemite Valley is crucial for anyone looking to enjoy the stunning natural beauty of this iconic location. With peak UV levels reaching a high of 12 around noon, awareness of the UV Index can help prevent sunburn and protect skin health for visitors exploring the great outdoors. Given Yosemite Valley's Csb climate, characterized by mild summers and high sun exposure, recognizing the risks associated with UV radiation becomes essential for safe enjoyment of activities like hiking and sightseeing. Don't let the sun catch you off guard—stay informed to make the most of your adventures while keeping your skin safe!
The UV Index reaches its peak intensity at 1 PM, soaring to an alarming 12. Early morning starts off gently, with indices of 1 at 7 AM and gradually rising to 2 by 8 AM. By 9 AM, the index jumps to 4, hinting at more intense sun exposure to come. As the day progresses, it escalates rapidly, hitting 7 by 10 AM and 9 at 11 AM. The sun is at its zenith at noon, with a robust 11. After this peak, a slight decline begins, but caution is still advised as the values remain significant, dropping to 8 at 3 PM and tapering off to 3 by 5 PM. The UV risk diminishes further into the evening, returning to a calmer 1 by 7 PM. Stay protected during those midday hours to enjoy the sun safely!
| 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 | 12 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 8 | very high | 15 min |
| 16:00 | 6 | high | 25 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, UV Index levels experience significant fluctuations, with the highest risk months occurring from April to August, where the UV Index reaches an extreme level of 12. During these months, the recommended burn time is as brief as 10 minutes, emphasizing the importance of protective measures against harmful UV radiation. Notably, March and September also present very high UV levels of 9 and 10, respectively, with a burn time of 15 minutes. In the winter months (January, November, December), UV exposure is less intense, categorized as moderate to high with burn times ranging from 25 to 30 minutes. Visitors and residents are advised to take extra precautions during high-risk months, such as wearing sunscreen, protective clothing, and seeking shade to minimize sun damage.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Chicago UVI | 3 | 4 | 6 | 8 | 9 | 10 | 10 | 9 | 8 | 6 | 4 | 2 |
| Brooklyn UVI | 3 | 5 | 6 | 8 | 10 | 10 | 9 | 9 | 8 | 6 | 4 | 2 |
| New York City UVI | 3 | 5 | 6 | 8 | 10 | 10 | 9 | 9 | 8 | 6 | 4 | 2 |
| Los Angeles UVI | 4 | 6 | 8 | 9 | 10 | 11 | 11 | 10 | 10 | 7 | 5 | 4 |
| Yosemite Valley | 4 | 6 | 9 | 11 | 12 | 12 | 12 | 11 | 10 | 7 | 5 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |