Last updated: June 2, 2025
Understanding the UV Index is essential for residents of Black River Falls, United States, where the climate can expose you to varying levels of solar radiation throughout the year. With peak UV levels reaching as high as 10 during midday hours, awareness of these fluctuations is crucial for prevention of sunburn and maintaining skin health. As a city nestled in a Dfb climate zone, the exposure to ultraviolet rays can pose significant risks, especially during the warmer months. By staying informed about the daily UV Index, you can enjoy the outdoors safely while protecting your skin from harmful effects.
The UV Index throughout the day shows a clear progression in intensity, peaking at a formidable 10 around noon. The morning starts off relatively mild, with values of 1 at 7:00 AM gradually rising to 4 by 9:00 AM. As the day unfolds, the index escalates swiftly, reaching 8 by 11:00 AM and then hitting its zenith of 10 at 12:00 PM and 1:00 PM. After this peak, there’s a noticeable decline; by 3:00 PM, it drops to 8 and continues to decrease until it settles back at 1 by 7:00 PM. This data underscores the importance of sun protection during the peak hours of 11:00 AM to 1:00 PM, when UV exposure is highest.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 2 | low | 45 min |
| 09:00 | 4 | moderate | 30 min |
| 10:00 | 6 | high | 25 min |
| 11:00 | 8 | very high | 15 min |
| 12:00 | 10 | very high | 15 min |
| 13:00 | 10 | very high | 15 min |
| 14:00 | 9 | 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, UV Index levels undergo significant changes, with notable increases during the warmer months. January and December experience low UV exposure (Index 2), allowing for longer burn times of 45 minutes. However, as early as February, the index rises to 4, indicating a moderate risk with a burn time of 30 minutes. The high-risk months peak from April to August, with UV Index values reaching 8 to 10 and a burn time as brief as 15 minutes—these months are categorized as very high risk for sunburn. In September, UV exposure decreases slightly to a 7, still classified as high risk, necessitating caution with a burn time of 25 minutes. As temperatures drop in October and November, the index falls back to moderate levels, allowing for burn times of 30 minutes. It is crucial for both visitors and residents to take protective measures—such as wearing sunscreen, protective clothing, and seeking shade—particularly during the April to August period, when the risk of skin damage from UV exposure is at its highest.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Black River Falls | 2 | 4 | 5 | 8 | 8 | 10 | 10 | 9 | 7 | 5 | 3 | 2 |
| 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 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |