Last updated: May 3, 2025
Understanding the UV Index is crucial for residents and visitors of West Yellowstone, United States, especially given its unique climate characterized by cool summers and high-altitude exposure. With UV levels peaking at a hazardous 11 around midday, it’s essential to prioritize sunburn prevention and overall skin health. By staying informed about daily UV risks, you can better protect yourself against harmful effects, ensuring enjoyable outdoor experiences in this stunning natural landscape. Whether hiking in the summer sun or exploring Yellowstone’s breathtaking vistas, awareness of the UV Index is your best defense against overexposure.
The UV Index sharply rises throughout the morning, starting at a gentle 1 at 7:00 AM and climbing gradually to 3 by 9:00 AM. As the sun reaches its peak, the intensity escalates dramatically, hitting a striking 10 at noon. By 1:00 PM and 2:00 PM, the index reaches its zenith at 11, indicating a high potential for skin damage without protection. As the afternoon progresses, the levels begin to dip, falling to 9 at 3:00 PM, and gradually decreasing to 3 by 6:00 PM, before finally settling back at 1 by 7:00 PM. For outdoor enthusiasts, it's crucial to be mindful of this UV fluctuation: stay protected during the peak 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 | 3 | moderate | 30 min |
| 10:00 | 6 | high | 25 min |
| 11:00 | 8 | very high | 15 min |
| 12:00 | 10 | very high | 15 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 9 | 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 |