Last updated: July 2, 2025
Understanding the UV Index is crucial for outdoor adventurers and visitors to the Grand Canyon, where the stunning landscapes are complemented by a climate ideal for exploration. High UV levels, peaking at 12 around noon, indicate that sunburn can occur quickly without adequate protection. As the Grand Canyon is classified under the BSk climate zone, it often boasts clear skies and abundant sunshine, increasing the risk of harmful UV exposure throughout the day. By staying informed about UV levels, you can safeguard your skin health and enjoy your time in this natural wonder safely and responsibly.
As the sun rises, the UV Index starts off low at 1 at 07:00, making it a safe time for outdoor activities. By 08:00, it increases to 3, signaling the need for some sun protection. The intensity peaks sharply during the late morning and early afternoon, hitting a maximum of 12 at both 12:00 and 13:00—a strong reminder to seek shade and reapply sunscreen if you’re out and about. As the day progresses, the index gradually drops; with 8 at 15:00 and 5 by 16:00, providing a more manageable exposure level. As evening approaches, the UV Index returns to a safe 1 by 18:00, making twilight hours pleasant for a leisurely stroll.
| 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 | 8 | very high | 15 min |
| 11:00 | 11 | extreme | 10 min |
| 12:00 | 12 | 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 exhibit significant seasonal changes, with high-risk months predominantly from February to August. The UV Index peaks at 12 during the summer months of May, June, July, and August, categorizing exposure as extreme and resulting in a burn time of just 10 minutes. Visitors and residents are strongly advised to take protective measures during these times, such as wearing sunscreen, protective clothing, and seeking shade during peak hours. Conversely, January, November, and December present moderate UV levels (Index 4-5), where burn times extend to 30 minutes, indicating a lower risk of UV-related harm. As seasons transition, awareness and proactive sun safety become crucial in protecting skin health.
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 |
| Grand Canyon | 4 | 7 | 9 | 11 | 12 | 12 | 12 | 11 | 10 | 8 | 5 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |