Last updated: July 2, 2025
Understanding the UV Index is essential for residents and visitors in Flagstaff, United States, where the combination of high altitude and intense sunlight can elevate UV exposure risks. Being aware of UV levels is crucial for protecting your skin from harmful effects like sunburn and prolonged damage that can lead to skin cancer. In Flagstaff's temperate climate, UV indices can peak at 13 during midday hours, making it imperative to take precautions from 10 AM to 2 PM when the sun's intensity is greatest. By staying informed about the UV Index, you can enjoy outdoor activities while safeguarding your skin health and well-being.
As the sun rises, the UV Index gradually climbs, beginning at a mild 1 by 07:00. By 08:00, it increases to 3, signaling the start of a sun-soaked day. Come 09:00, it jumps to 6, and by 10:00, it soars to a peak of 9. The intensity reaches its zenith at 11:00 with an impressive 11, followed by a blistering high of 13 at 12:00. The afternoon sees a slight decline, with the index dropping to 12 at 13:00, and then stabilizing at 11 from 14:00 to 15:00. As the sun begins its descent, the UV Index decreases to 5 at 16:00, and falls to 3 by 17:00. Finally, as twilight sets in, the UV levels drop back to 1 at 18:00 and remain steady until 19:00. Stay sun-smart! 🌞
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 3 | moderate | 30 min |
| 09:00 | 6 | high | 25 min |
| 10:00 | 9 | very high | 15 min |
| 11:00 | 11 | extreme | 10 min |
| 12:00 | 13 | extreme | 10 min |
| 13:00 | 12 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 8 | very high | 15 min |
| 16:00 | 5 | moderate | 30 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, UV Index levels fluctuate, indicating varying risks for skin exposure. The high-risk months are primarily from March to September, where the UV Index peaks at 13 in both June and July, classified as extreme, resulting in a burn time of only 10 minutes. Visitors and residents should prioritize skin protection during these months with appropriate sunscreen, protective clothing, and seeking shade during peak hours. The months of February and October also present very high UV levels of 8, with shorter burn times of 15 minutes, necessitating caution. Conversely, January, November, and December feature moderate to high UV levels, with more forgiving burn times, though protective measures should still be considered. Emphasizing sun safety year-round is essential for both health and well-being.
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 |
| 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 |
| Flagstaff | 5 | 8 | 9 | 11 | 12 | 13 | 13 | 12 | 11 | 8 | 6 | 4 |