Last updated: June 2, 2025
Understanding the UV Index is crucial for residents and visitors of West Yellowstone, United States, where the stunning natural beauty can sometimes expose you to hidden dangers from the sun. The UV Index not only helps in predicting sunburn risk but also plays a significant role in maintaining long-term skin health. With a subarctic climate (Dfc), West Yellowstone experiences diverse weather patterns, but during the summer months, UV levels can skyrocket, reaching a peak of 11 around noon. This underscores the importance of being aware of the UV Index to safeguard your skin while enjoying outdoor activities in this breathtaking region.
At dawn, as the sun begins to rise, the UV Index (UVI) starts low at 1 at 7:00 AM, indicating minimal UV exposure. By 8:00 AM, it gently climbs to 2, becoming more noticeable. The peak UV intensity occurs around noon, reaching a significant 11 by 12:00 PM and remaining there until 2:00 PM, marking the hours of greatest caution for outdoor activities. Afterward, it begins to taper off, dropping to 10 by 3:00 PM, and steadily declines through the late afternoon and into the evening, reaching back down to 1 by 7:00 PM. This data serves as a vital reminder for sun protection, especially during the midday hours when the UVI is at its highest!
| 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 | 6 | high | 25 min |
| 11:00 | 9 | very high | 15 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 10 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 3 | moderate | 30 min |
| 19:00 | 1 | low | 45 min |
The UV Index exhibits significant seasonal variation, peaking during the summer months of May through August, where it reaches extreme levels of 11. Specifically, April sees a rise to a very high index of 9, and as summer approaches, it steadily climbs, with the lowest burn time for those months decreasing to just 10 minutes. In contrast, January and February have a moderate index of 3 and 5 respectively, allowing for safe sun exposure for up to 30 minutes. Visitors and residents should exercise heightened caution during the high-risk months of March to August, particularly from May to July when the sun's intensity is extreme. It’s advisable to wear protective clothing, apply sunscreen liberally, and seek shade during peak hours to minimize the risk of sunburn and long-term skin damage. As we move into the fall and winter months, the UV Index decreases, allowing for safer exposure, particularly in November and December when the burn time is significantly longer.
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 |
| West Yellowstone | 3 | 5 | 7 | 9 | 11 | 11 | 11 | 10 | 9 | 6 | 4 | 2 |
| Los Angeles UVI | 4 | 6 | 8 | 9 | 10 | 11 | 11 | 10 | 10 | 7 | 5 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |