Last updated: May 3, 2025
In Chattanooga Valley, understanding the UV Index is crucial for protecting your skin and ensuring your overall health. The UV Index measures the strength of ultraviolet radiation at a specific time, helping residents prevent sunburn and mitigate long-term skin damage. With the region's Cfa climate resulting in warm summers and significant sun exposure, the midday UV levels can reach as high as 11—indicating a very high risk of harm from unprotected sun exposure. By being aware of these daily fluctuations, you can make informed decisions about sun safety, allowing you to enjoy the beautiful outdoors without compromising your health.
As the sun rises, the UV Index begins to climb gently, peaking at a moderate 1 at 7:00 AM and maintaining that level until 9:00 AM. By 10:00 AM, the intensity sharply rises to 5, and by midday, it reaches a remarkable 9. The afternoon sees the UV Index soar to its maximum of 11 at both 1:00 PM and 2:00 PM, indicating a high risk of harm from unprotected sun exposure. As the day progresses, the index gradually declines, hitting 7 at 4:00 PM and settling to a safer 2 by 6:00 PM, before returning to 1 after sunset. This fluctuation underscores the importance of sun protection during peak hours, particularly between 10:00 AM and 3:00 PM.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 1 | low | 45 min |
| 09:00 | 2 | low | 45 min |
| 10:00 | 5 | moderate | 30 min |
| 11:00 | 7 | high | 25 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 11 | extreme | 10 min |
| 15:00 | 9 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 5 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, the UV Index exhibits significant seasonal changes, with the highest levels occurring in May, June, and July, where it reaches an extreme index of 11. These months pose the greatest risk for sunburn, with a quick burn time of just 10 minutes. The high-risk months to be particularly cautious are March through August, as the UV Index remains very high to extreme during this period. Visitors and residents should take proactive measures, including wearing protective clothing, applying broad-spectrum sunscreen, and seeking shade during peak sunlight hours, especially from 10 a.m. to 4 p.m. Conversely, in the winter months of December and January, the UV Index is lower at 3-4, indicating a moderate risk with a burn time of 30 minutes, allowing for slightly more leeway in sun exposure. Regardless of the season, it is essential to stay informed and protect yourself from harmful UV rays.
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 |
| Chattanooga Valley | 4 | 6 | 8 | 10 | 11 | 11 | 11 | 10 | 9 | 7 | 5 | 3 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |