Last updated: June 2, 2025
Understanding the UV Index is crucial for residents of Great Falls, as it serves as a vital tool for protecting skin health against harmful ultraviolet radiation. With UV levels peaking during the midday hours—including a notable index of 11 at 1 PM—being aware of the risks associated with sun exposure can help prevent painful sunburns and long-term skin damage. Typically characterized by its Cfa climate, Great Falls experiences significant sunlight, making it essential for locals to monitor UV levels throughout the day to enjoy the outdoors safely while safeguarding their skin.
As the sun rises, the UV Index begins its modest ascent, starting at a gentle 1 around 7:00 AM and 8:00 AM. By 9:00 AM, it picks up to 3, hinting at a sunnier day ahead. The peak intensity occurs from 11:00 AM to 1:00 PM, where it skyrockets to a striking 10 at 12:00 PM, reaching an impressive 11 by 1:00 PM—perfect for those sun-seeking adventurers! However, after this zenith, the UV Index gradually declines, dropping to 9 by 3:00 PM and further easing to a 4 by 5:00 PM. By 6:00 PM, it falls to 2, and as the sun sets, it returns to a safe 1 by 7:00 PM. Remember to take precautions during those peak hours to protect your skin from harmful rays!
| 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 | 8 | very high | 15 min |
| 12:00 | 10 | very high | 15 min |
| 13:00 | 11 | extreme | 10 min |
| 14:00 | 10 | very high | 15 min |
| 15:00 | 9 | very high | 15 min |
| 16:00 | 7 | high | 25 min |
| 17:00 | 4 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, seasonal UV changes indicate notable variations in sun exposure risk. The high-risk months are concentrated from March to August, peaking in June and July when the UV Index reaches an extreme level of 11, allowing for a dangerous burn time of just 10 minutes. In contrast, the UV Index in January and December presents a moderate risk with a burn time of 30 minutes. As visitors and residents plan outdoor activities, it is crucial to be vigilant during the high UV periods, particularly in March through August. It's advisable to wear protective clothing, apply sunscreen liberally, and seek shade during peak sun hours to minimize skin damage and maintain safety.
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 |
| Los Angeles UVI | 4 | 6 | 8 | 9 | 10 | 11 | 11 | 10 | 10 | 7 | 5 | 4 |
| Great Falls | 4 | 7 | 8 | 10 | 10 | 11 | 11 | 10 | 9 | 8 | 6 | 4 |
| Houston UVI | 5 | 8 | 9 | 11 | 11 | 12 | 12 | 11 | 10 | 9 | 7 | 5 |