Last updated: July 2, 2025
Understanding the UV Index is crucial for residents of Louisville, United States, where the combination of a humid subtropical climate and sunny days can lead to increased skin exposure to harmful ultraviolet radiation. Being aware of UV levels is essential for preventing sunburn and maintaining skin health, particularly during peak hours when values can soar to 11, indicating extreme risk. As the sun reaches its zenith in the afternoon, residents should take proactive measures to protect themselves from potential skin damage. With typical UV exposure in Louisville fluctuating throughout the day, knowing how to read the UV Index can empower individuals to enjoy the outdoors safely while minimizing their risk.
Expect a sunny day with a fluctuating UV Index that peaks at 11 around midday. The morning starts off gentle, with values rising from 1 at 7:00 AM to 4 by 9:00 AM. As the sun climbs higher, the UV Index escalates sharply, reaching 9 by 11:00 AM and hitting its highest point of 11 at both 12:00 PM and 1:00 PM. After the sun’s zenith, the UV levels gradually decline, dropping to 10 at 2:00 PM and tapering off to 1 by 7:00 PM. Remember to protect your skin during those peak hours for a safe and enjoyable day outdoors!
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | low | 45 min |
| 09:00 | 4 | moderate | 30 min |
| 10:00 | 6 | high | 25 min |
| 11:00 | 9 | very high | 15 min |
| 12:00 | 11 | extreme | 10 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 10 | very high | 15 min |
| 15:00 | 8 | very high | 15 min |
| 16:00 | 6 | high | 25 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
As the seasons change, so does the UV Index, which significantly impacts exposure levels throughout the year. January starts with a moderate UV Index of 4, allowing for a burn time of 30 minutes. However, February ramps up to a high index of 7, with a reduced burn time of 25 minutes. The peak months, from March through August, experience extreme UV levels, particularly in May and June, where the UV Index reaches 11 and burn times shrink to just 10 minutes. September and October see a slight decrease, yet still maintain a very high index of 9 and 8, respectively. The year concludes with lower levels in November and December. Visitors and residents should take special care during the high-risk months from March to August, ensuring proper sun protection measures, such as wearing sunscreen, hats, and protective clothing, to mitigate the risk of UV-related harm.
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 |
| Louisville | 4 | 7 | 8 | 10 | 11 | 11 | 11 | 11 | 9 | 8 | 6 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |