Last updated: June 2, 2025
Understanding the UV Index is crucial for residents of the continental United States, especially in regions characterized by a Dfa climate. Awareness of UV levels helps protect against sunburn and long-term skin health issues. Peak UV exposure typically occurs between 10 AM and 2 PM, reaching a notable maximum of 10 at midday—a time when even brief sun exposure can cause harm. By staying informed about UV levels, you can enjoy the outdoors safely while minimizing risks associated with high UV radiation.
The UV Index is a dynamic measure of solar intensity throughout the day, peaking dramatically at 12:00 PM with a notable 9, reaching its zenith at 1:00 PM and 2:00 PM with a maximum value of 10. During this period, it's essential to protect your skin from harmful UV rays. Early morning hours remain quite low, peaking at just 1 by 08:00 AM, while by 10:00 AM the index climbs to 5. As the sun continues to rise, it climbs swiftly to 7 by 11:00 AM, making midday the crucial time for sunscreen and shade. As the afternoon wanes, the UV Index gradually decreases, falling back to 5 by 5:00 PM, and finally settling at 1 by 7:00 PM, signaling a safe return to outdoor activities. Stay vigilant and enjoy the sunshine safely!
| 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 | 10 | very high | 15 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 |
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 |