Last updated: June 2, 2025
Understanding the UV Index is crucial for residents and visitors in Keystone, United States, where the sun's rays can be deceptively intense, especially during the summer months. With a Dfc climate, characterized by cool summers and ample sunshine, awareness of UV levels is vital for preventing sunburn and protecting long-term skin health. The UV Index here peaks at 14 around midday, signaling a risk of harm from unprotected sun exposure. By keeping an eye on these levels, you can enjoy everything Keystone has to offer while safeguarding your skin from the damaging effects of UV radiation.
As the day unfolds, the UV Index peaks dramatically, reminding us to take heed of the sun’s intensity. Starting at a safer 1 at 7:00 AM, it rises steadily, hitting 3 by 8:00 AM and climbing to a moderate 5 by 9:00 AM. The sun begins to showcase its strength as it reaches 8 at 10:00 AM, before soaring to a critical 11 by 11:00 AM. The highest point of the day arrives at 13 and 14 between 12:00 PM and 1:00 PM, marking the most dangerous hours for sun exposure. As afternoon progresses, the intensity slightly wanes, dropping to 11 by 3:00 PM and then easing further to 8 at 4:00 PM. As the sun begins to lower, the UV Index falls to 5 by 5:00 PM, and concludes the day at a gentle 1 by 7:00 PM. Remember to protect your skin during those peak hours!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 3 | moderate | 30 min |
| 09:00 | 5 | moderate | 30 min |
| 10:00 | 8 | very high | 15 min |
| 11:00 | 11 | extreme | 10 min |
| 12:00 | 13 | extreme | 10 min |
| 13:00 | 14 | extreme | 10 min |
| 14:00 | 13 | extreme | 10 min |
| 15:00 | 11 | extreme | 10 min |
| 16:00 | 8 | very high | 15 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, UV exposure levels fluctuate significantly, with high-risk months typically occurring from March through September. During these months, the UV Index peaks, reaching extreme levels of 12 to 14 in April, May, June, and July, where the recommended burn time is as little as 10 minutes. Conversely, the UV Index remains lower during the winter months, with January and December registering a moderate Index of 4, allowing for a safer burn time of 30 minutes. Visitors and residents are advised to exercise caution and protection, particularly between March and September, by wearing sunscreen, protective clothing, and sunglasses during peak sunlight hours to minimize the risk of sunburn and long-term skin damage.
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 |
| Keystone | 4 | 6 | 9 | 12 | 13 | 14 | 13 | 12 | 11 | 7 | 5 | 4 |