Last updated: May 3, 2025
In Louisville, United States, understanding the UV Index is essential for protecting your skin and overall health. With the city’s Cfa climate, residents often face varying levels of UV exposure throughout the day, especially during peak hours where the index can soar to 11—potentially leading to sunburn and long-term skin damage. By staying informed about daily UV levels, you can take proactive measures to enjoy the sunshine safely, whether it’s applying sunscreen, seeking shade, or wearing protective clothing. Awareness of these UV risks is crucial for maintaining skin health, particularly in a city known for its vibrant outdoor activities.
During the day, the UV Index exhibits a striking pattern as it peaks in the late morning and early afternoon. Starting from a modest value of 1 at 07:00, the index gradually climbs, reaching 3 by 09:00. Expect a sharp increase around 10:00, when it soars to 5, and it doesn't stop there; by noon, it hits an impressive 10. The highest point of the day occurs at 13:00, with a peak of 11, indicating a critical time for sun exposure. As the afternoon progresses, the index begins to decline, falling to 10 at 14:00 and tapering off to 9 at 15:00. By evening, the UV Index diminishes steadily, finishing the day back at 1 by 19:00. This data emphasizes the importance of protective measures during the high noon hours when UV levels are at their most intense.
| 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 | 10 | very high | 15 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 10 | very high | 15 min |
| 15:00 | 9 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 4 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, UV Index levels exhibit noteworthy seasonal changes, with high-risk months identified from March to August, when exposure reaches very high or extreme levels. In March and April, the UV Index peaks at 9 and 10, respectively, indicating a transition into the more hazardous summer months. May through August experience the highest UV Index of 11, categorized as extreme, which necessitates diligent sun protection within a burn time of just 10 minutes. As September and October arrive, UV levels remain considerable, with a very high index of 9 and 8, and slowly tapering off towards the end of the year. It is crucial for both visitors and residents to take appropriate precautions during these months, such as wearing sunscreen, protective clothing, and seeking shade during peak hours to minimize the risk of UV-related 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 |
| Louisville | 4 | 7 | 9 | 10 | 11 | 11 | 11 | 11 | 9 | 8 | 6 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |