Last updated: August 1, 2025
Understanding the UV Index is crucial for residents of Louisville, United States, as it directly impacts skin health and sunburn prevention. With the city's Cfa climate, characterized by hot summers and mild winters, awareness of UV levels can help you protect yourself during peak sunlight hours, especially when the index reaches a high of 10 around noon. By staying informed, you can enjoy the outdoors while safeguarding your skin from the harmful effects of excessive UV exposure. Remember, knowledge is your best defense against sun-related health risks!
At dawn, the UV Index starts at a mild 1 by 07:00, gradually climbing to 2 by 08:00 as the sun rises. The warmth intensifies, reaching 4 at 09:00 and peaking at a significant 10 between noon and 14:00, signaling the need for sun protection. As the afternoon rolls in, the index begins to dip, settling at 8 by 15:00 before tapering off further to 5 at 16:00. By the evening, the UV levels gracefully descend back to 2 at 18:00 and return to a safe 1 by 19:00, marking a day's journey through varying sun exposure. Be mindful of the midday sun, and stay protected during those peak hours!
| 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 | 1 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, the UV Index reflects significant seasonal changes that affect sun exposure safety for both visitors and residents. From January to February, the UV levels remain moderate (3 to 5), allowing for a burn time of up to 30 minutes. A marked increase occurs in March, where the index rises to 7 (high exposure), reducing burn time to 25 minutes. The most critical months for UV exposure are April and May, with indices of 9 and 11, categorized as very high and extreme, where burn times drop to just 15 and 10 minutes respectively. June maintains this extreme risk, followed closely by a slight decrease in July (index of 10) and a resurgence in August and September (both at 9). October marks a return to high exposure (6), with burn times returning to 25 minutes, before descending back to moderate levels in November and December. Visitors and residents should be especially vigilant during April through September, utilizing appropriate sun protection measures, such as sunscreen, hats, and seeking shade, to minimize the risk of UV-related health issues.
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 | 11 | 11 | 10 | 9 | 9 | 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 |