Last updated: May 3, 2025
In the Continental United States, understanding the UV Index is crucial for maintaining skin health and preventing sunburn. With peak levels reaching a dangerous 10 during midday, residents must stay vigilant about their sun exposure, especially during the warmer months typical of a Dfa climate. By familiarizing yourself with daily UV levels, you can make informed decisions about outdoor activities, seek shade, and apply sunscreen effectively, ensuring that your skin remains protected against harmful ultraviolet rays. Being aware of the UV Index can significantly reduce your risk of skin damage and enhance your overall well-being.
As the sun rises, the UV Index begins its gradual ascent, starting at a mild 1 at 07:00 and 08:00. However, by 09:00, it jumps to 3, indicating a greater need for sun protection. The intensity peaks at 12:00 with a 9, reaching a maximum of 10 during the 13:00 and 14:00 hours, showcasing the sun's strongest rays. As the day progresses, the UV Index begins to decline, dropping to 8 at 15:00, then further to 6 by 16:00. The evening brings a welcome reduction in UV exposure, with the index falling to 4 at 17:00, and tapering off to 2 and 1 as the sun sets at 18:00 and 19:00. It's clear that the mid-day hours demand the most caution for sun safety!
| 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 | 4 | 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 | 10 | very high | 15 min |
| 15:00 | 8 | very high | 15 min |
| 16:00 | 6 | high | 25 min |
| 17:00 | 4 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, the UV Index experiences significant fluctuations, with the highest levels occurring during the summer months. High-risk months for UV exposure include April through September, when the UV Index reaches very high levels of 9 or 10, significantly reducing the safe burn time to just 15 minutes. Visitors and residents are strongly advised to take precautions during these months, including wearing protective clothing, applying broad-spectrum sunscreen, and seeking shade during peak sun hours. Conversely, the winter months of December and January present lower UV risks, with indices of 2 and 3, allowing for safer exposure times of 30 to 45 minutes. Overall, awareness of seasonal changes in UV levels is crucial for protecting skin health 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 |
| Continental | 3 | 5 | 6 | 9 | 9 | 10 | 10 | 9 | 8 | 6 | 4 | 2 |
| 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 |