Last updated: June 2, 2025
Awareness of the UV Index is crucial for residents of Cheyenne, as it directly impacts skin health and sunburn prevention. Understanding the varying levels of UV radiation throughout the day is essential for protecting yourself from potential harm. With a humid subtropical climate (Cfa), Cheyenne experiences significant UV exposure, especially during peak hours around noon, where the index can reach a high of 11. By staying informed and taking necessary precautions based on the UV Index, you can enjoy the sunny days without compromising your skin health.
The hourly UV Index paints a vivid picture of the sun's intensity throughout the day. Starting off gently in the early morning, with maximum readings of 1 at 07:00 and 08:00, it gradually begins to climb. By 09:00, it reaches 3, signaling a noticeable increase in UV exposure. The sun peaks dramatically at 12:00, soaring to a 10, reaching its zenith with a maximum of 11 at both 13:00 and 14:00—a prime time for sun protection. As the afternoon slips into evening, the UV Index begins to recede, dropping to 8 by 16:00, and then tapering off to 5 at 17:00. The day winds down with a safe 3 at 18:00 and returns to a manageable 1 by 19:00, reminding us to stay vigilant and enjoy the sun responsibly throughout the day.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 1 | 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 | 8 | very high | 15 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 demonstrates notable seasonal changes, with the most intense exposure occurring from April to August. During these months, the UV Index reaches extreme levels (10-12), significantly reducing the burn time to just 10 minutes. March and September also pose risks with very high levels (8-10), allowing for a burn time of only 15 minutes. Consequently, February and October present high levels (6-7), where protective measures are still advised with adjusted burn times of 25 minutes. Residents and visitors should exercise caution and protect their skin, especially during the high-risk months of April through August, by using sunscreen, wearing protective clothing, and limiting sun exposure during peak hours.
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 |
| Cheyenne | 4 | 6 | 8 | 10 | 11 | 11 | 12 | 11 | 10 | 7 | 5 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |