Last updated: May 3, 2025
Understanding the UV Index is crucial for everyone in Knoxville, Tennessee, where the sun can shine brightly, especially during warmer months. Being aware of UV levels is not just about avoiding sunburn; it’s essential for maintaining long-term skin health and lowering the risk of skin cancers. Knoxville's Dfa climate means warm summers with intense UV exposure, peaking in the midday hours when the index can reach as high as 9. By keeping an eye on the UV Index, you can enjoy outdoor activities safely while protecting your skin from harmful rays.
The UV Index for the day showcases a notable rise in intensity as the sun climbs higher in the sky. Starting at a low of 1 at 7:00 AM, the index gradually increases to a moderate level of 3 by 9:00 AM. However, from 10:00 AM onward, things heat up significantly, peaking at a scorching 9 from noon to 2:00 PM. As the afternoon progresses, the UV Index gradually dips back to a friendly 3 by 5:00 PM, then descends further to 1 by the time evening sets in. This pattern underscores the importance of sun protection during peak hours, especially between 11:00 AM and 2:00 PM, when UV levels are at their 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 | 9 | very high | 15 min |
| 14:00 | 9 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 5 | moderate | 30 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
The UV Index shows significant seasonal changes, peaking during the summer months. January and December have a moderate UV Index of 3, allowing for prolonged exposure without risk of sunburn (30 minutes). As we transition into March, the risk increases with a high UV Index of 6 and a reduced burn time of 25 minutes. April through July are the highest risk months, with the UV Index reaching an extreme 11 in both June and July, allowing for just 10 minutes of safe exposure. During these months, it is crucial for both visitors and residents to take precautions such as wearing sunscreen, protective clothing, and seeking shade. As the summer fades into August and September, the UV Index remains very high at 9 and 8, but burn times extend to 15 minutes. As we move into the fall and winter, the UV levels decline, returning to moderate levels by November. Visitors and residents should stay alert to these changes throughout the year to ensure proper sun safety.
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 |
| Knoxville | 3 | 5 | 6 | 8 | 9 | 11 | 11 | 9 | 8 | 6 | 4 | 3 |
| 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 |