Last updated: June 2, 2025
Understanding the UV Index is crucial for residents of Louisville, as it serves as a valuable tool in protecting your skin from harmful ultraviolet rays. With summer temperatures soaring in this Cfa climate zone, the sun's intensity can pose significant risks, particularly during peak hours when the UV Index can reach levels as high as 11. Being aware of these UV levels is essential for preventing sunburn and maintaining long-term skin health. Throughout the day, especially between noon and 2 PM, it's vital to take precautionary measures to shield yourself from excessive exposure, ensuring you enjoy the vibrant outdoors safely.
The UV Index begins the day with a gentle rise, starting at a modest 1 at 07:00 and 08:00, ideal for those seeking gentle morning sunlight. As the sun climbs higher, the index sharply escalates, peaking at a striking 11 around 14:00, indicating a significant risk of harm from unprotected sun exposure. Wear sunscreen and protective clothing if you're outdoors during peak hours! The afternoon shows a gradual decline, dipping to 9 at 15:00, and further waning to 1 by 19:00, marking a return to safer levels as evening approaches. Stay sun-smart and enjoy 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 | 7 | high | 25 min |
| 12:00 | 9 | very high | 15 min |
| 13:00 | 10 | very high | 15 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 | 3 | moderate | 30 min |
| 19:00 | 1 | low | 45 min |
As the seasons change, so does the UV Index, which indicates the strength of ultraviolet radiation and the associated risk of harm from sun exposure. High-risk months for UV exposure typically occur from March through September, peaking in June with an extreme Index of 11 and a burn time of just 10 minutes. April and May are also notably hazardous, with very high UV ratings of 9 and 10 respectively. During these months, it is crucial for visitors and residents to take protective measures, such as wearing sunscreen, protective clothing, and seeking shade during peak hours. Conversely, during the winter months of January, November, and December, the UV Index is moderate, allowing for longer exposure times of up to 30 minutes without immediate risk. Always stay informed and prioritize sun safety to enjoy the outdoors responsibly throughout the year.
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 |
| Louisville | 3 | 5 | 7 | 9 | 10 | 11 | 10 | 10 | 8 | 7 | 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 |