Last updated: June 2, 2025
Understanding the UV Index is essential for residents of Butte, United States, especially given the city's varied climate and outdoor lifestyle. With UV levels peaking at a dangerous 11 during midday hours, awareness is key to preventing sunburn and protecting skin health. The Dfa climate of Butte means that while summers can be warm, the UV rays can be deceptively intense, posing risks even on seemingly mild days. Stay informed about UV exposure to enjoy the outdoors safely and maintain healthy skin throughout the year!
As the day unfolds, the UV Index begins its ascent with a gentle 1 at 7:00 AM, gradually climbing to a moderate 3 by 9:00 AM. The sun's strength becomes undeniable by 10:00 AM, peaking at a robust 11 around 1:00 PM—the highest point of the day. Even as the afternoon progresses, the index slowly recedes, measured at 9 at 3:00 PM and continuing to dip into the evening, reaching 1 by 7:00 PM. Remember to protect your skin during those peak hours—especially between 11 AM and 3 PM—when UV exposure is at its highest!
| 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 | 7 | high | 25 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 10 | very high | 15 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 |
Throughout the year, the UV Index exhibits notable seasonal fluctuations, peaking during the summer months. From January to April, the index gradually rises from 3 to 8, indicating a shift from moderate to very high risk. The risk of harm significantly increases in May and reaches its zenith in June with an extreme index of 11. High-risk months include March (UV Index 6) and April (UV Index 8), transitioning to very high risks from May through September when the index remains above 8. During these peak months, particularly in June, visitors and residents are strongly advised to take precautions: seek shade, wear protective clothing, and apply sunscreen regularly to mitigate skin damage. As the year progresses towards October and November, the UV Index decreases, returning to moderate levels by December, where exposure risks are lower and burn time increases to 45 minutes. This seasonal insight highlights the importance of adjusting sun safety practices throughout the year.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Butte | 3 | 5 | 6 | 8 | 9 | 11 | 10 | 10 | 8 | 5 | 3 | 2 |
| 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 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |