Last updated: June 2, 2025
In Alta Sierra, United States, staying informed about the UV Index is crucial for protecting your skin from harmful ultraviolet radiation. With UV levels peaking at 12 during midday hours, understanding these measurements can significantly aid in sunburn prevention and maintaining long-term skin health. Alta Sierra's BSk climate brings unique challenges, as the combination of high elevation and clear skies can amplify UV exposure, putting residents and visitors alike at greater risk for sun damage. Equip yourself with the knowledge of when to seek shade and how to wear protective clothing, ensuring you enjoy the outdoors safely!
As the sun rises, the UV Index begins its ascent, starting at a mild 1 at 07:00 and gradually climbing throughout the morning. By 09:00, it reaches a moderate 5, signaling the need for some sun protection. The intensity peaks around 12:00, with a high of 12, which indicates very high levels of UV radiation. Hereafter, the index gently declines, tapering off to 9 by 15:00, before easing down to 4 by 17:00. As the evening unfolds, the UV risk diminishes, dropping to 2 by 18:00 and finally returning to 1 at 19:00. This hourly UVI data underscores the importance of being mindful of sun exposure, especially during the midday hours when UV levels are at their highest.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | low | 45 min |
| 09:00 | 5 | moderate | 30 min |
| 10:00 | 7 | high | 25 min |
| 11:00 | 10 | very high | 15 min |
| 12:00 | 12 | extreme | 10 min |
| 13:00 | 12 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 9 | very high | 15 min |
| 16:00 | 6 | high | 25 min |
| 17:00 | 4 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
As we observe seasonal changes in the UV Index, it becomes clear that higher levels of ultraviolet radiation occur during the warmer months. The high-risk months peak from March to August, with May and June reaching extreme levels (UV Index 11-12) and burn times as low as 10 minutes. Visitors and residents are strongly advised to take precautions during these months by seeking shade, wearing protective clothing, and using sunscreen, especially between 10 AM and 4 PM when UV exposure is at its highest. January, November, and December are comparatively safer, with moderate UV levels (Index 4-5) and longer burn times of 30 minutes. Staying informed about the UV Index is essential for maintaining skin health year-round.
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 |
| Alta Sierra | 4 | 6 | 9 | 10 | 11 | 12 | 12 | 11 | 10 | 8 | 5 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |