Last updated: May 3, 2025
Understanding the UV Index is essential for residents and visitors of Big Sky, Montana, where the unique climate can lead to elevated sun exposure risks. As one of the highest peaks in the Northern Rockies, Big Sky's stunning landscape is often coupled with strong UV radiation, particularly during midday hours when the UV Index can soar to levels of 10 and 11. Being aware of UV levels is crucial for preventing painful sunburns and protecting skin health, helping you enjoy outdoor activities safely. Whether you're skiing down slopes or hiking in the summer sun, understanding UV exposure is key to making informed decisions about sun protection in this picturesque mountain town.
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 |
As the year progresses, the UV Index experiences noticeable changes, indicating varying levels of sun exposure risk. During the winter months, specifically January and February, UV levels remain moderate at 3 and 4 respectively, with a burn time of 30 minutes. However, spring ushers in a marked increase, with March reaching a high of 7 and April escalating to 9. The summer months of May, June, and July present extreme UV levels, peaking at 11 in May and June, while August begins to decline slightly but remains very high at 10. Autumn steps in gradually reducing risk, with September at 9 and October at 6. November and December boast lower levels of 4 and 2, indicating a return to moderate and low exposure risks. Visitors and residents should exercise caution, particularly during the high-risk months of April through August, where sun exposure can lead to severe skin damage in as little as 10 to 15 minutes. It is advisable to seek shade, wear protective clothing, and apply sunscreen consistently during these peak times to safeguard against harmful UV radiation.
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 |
| Big Sky | 3 | 4 | 7 | 9 | 11 | 12 | 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 |