Last updated: July 2, 2025
In West Yellowstone, understanding the UV Index is essential for protecting your skin and overall health. The UV Index measures the strength of ultraviolet radiation from the sun, which can lead to sunburn and increase the risk of skin ailments, making awareness particularly important in this scenic area. Nestled in a Dfc climate zone, West Yellowstone experiences varied weather conditions, but during the summer, UV levels can peak significantly—reaching a critical level of 11 around midday. By being mindful of the UV Index, residents and visitors can take proactive steps to ensure their enjoyment of the great outdoors while safeguarding their skin from harmful rays.
As the day progresses, the UV Index rises dramatically, peaking at a striking 11 between 1:00 PM and 2:00 PM. Starting from a modest 1 at 7:00 AM, the index steadily climbs, reaching 2 by 8:00 AM and hitting 5 by 10:00 AM. The real intensity kicks in around 11:00 AM, recording an 8, before soaring to its maximum of 10 at noon. After the midday peak, the index begins to decline but still remains significant with a 10 at 3:00 PM and dips to 7 by 4:00 PM. As the sun sets, the UV radiation decreases, trailing off to a 3 at 6:00 PM and finally settling back to 1 by 7:00 PM, marking a gradual end to the day’s sun exposure. Stay protected!
| 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 | 5 | moderate | 30 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 | 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 |