Last updated: July 2, 2025
Understanding the UV Index is essential for residents of Decorah, United States, where the climate can lead to significant sun exposure throughout the year. Awareness of UV levels not only helps prevent painful sunburns but also supports long-term skin health by reducing the risk of skin cancer. With peak UV levels reaching a high of 10 around noon, it's crucial for locals to monitor these readings, especially during the warmer months when the risk of overexposure is at its highest. Remember that even on cloudy days, UV rays can penetrate through, so being informed is key to enjoying the beautiful Decorah outdoors safely.
As the sun rises, the UV Index begins its ascent, peaking at an invigorating 10 by 1:00 PM. Early morning, from 7:00 AM to 8:00 AM, sees a mild 1 to 2, making it a perfect time for a leisurely stroll. By 9:00 AM, the UV Index reaches 3, signaling a need for some sun protection. The real intensity kicks in around 11:00 AM, hitting 8, and just after noon, it soars to its daily maximum of 9. The afternoon hours see a slight decline, with values tapering from 9 at 2:00 PM to 6 by 4:00 PM. As daylight wanes, the UV Index gently drops to 1 by 7:00 PM, wrapping up a day of vibrant sunlight but reminding us to stay vigilant during those peak hours. Remember to reapply sunscreen and seek shade to keep safe while enjoying those sunny moments!
| 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 | 6 | high | 25 min |
| 11:00 | 8 | very high | 15 min |
| 12:00 | 9 | 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, the UV Index shows significant seasonal changes that impact sun safety for residents and visitors. From April to September, the UV Index peaks, reaching levels as high as 10 in the summer months of June and July. This indicates a very high exposure category, with a reduced burn time of only 15 minutes during these months. Conversely, during the winter months of December through February, the UV Index is considerably lower, ranging from 2 to 4, with a burn time of 30 to 45 minutes. Therefore, visitors and residents should be especially cautious during the high-risk months of April to September, and take appropriate protective measures, such as wearing sunscreen, protective clothing, and seeking shade, to minimize their risk of UV exposure.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Decorah | 3 | 4 | 5 | 8 | 9 | 10 | 10 | 9 | 8 | 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 |