Last updated: July 2, 2025
Understanding the UV Index is crucial for protecting your skin in Missoula, where the climate can intensify sun exposure, especially during the warmer months. With UV levels peaking at 10 around midday, awareness of these fluctuations can help prevent painful sunburns and long-term skin damage. Even in a temperate climate like Missoula's Dfb zone, it's essential to recognize that UV radiation can be deceptive on cooler days. Stay informed and shield yourself from the sun's harmful effects by keeping an eye on the UV index, ensuring that your skin remains healthy and protected throughout the year.
As the sun rises, the UV Index starts off low, hitting just 1 by 07:00 and maintaining that level through 08:00. However, as the morning progresses, anticipation builds with a steady climb to 3 by 09:00 and peaking at a noteworthy 5 by 10:00. The intensity escalates sharply, reaching a maximum of 10 between 13:00 and 14:00, indicating a significant risk for unprotected skin. Gradually, the UV Index begins to decline, dropping back to 9 at 15:00 and easing down to 5, 3, and finally 2 as the day winds down through 17:00 to 19:00. A day to remember for sun seekers, but remember to apply that sunscreen during peak hours!
| 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 | 2 | low | 45 min |
Throughout the year, UV Index levels exhibit significant seasonal variation. January and December have low UV exposure, with indices of 2, allowing for a lengthy burn time of 45 minutes. As we transition to February (UV Index 4) and March (UV Index 6), the risk escalates to moderate and high, reducing safe exposure time to 30 and 25 minutes, respectively. The peak months for UV exposure occur during April to August, with indices reaching a high of 10 in June and July, categorized as very high and necessitating a brief burn time of just 15 minutes. By October, the index decreases to 5, then further settles at 3 in November. Residents and visitors are advised to exercise caution during the high-risk months of April through August, using sunscreen, protective clothing, and seeking shade to minimize the risk of skin damage.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Missoula | 2 | 4 | 6 | 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 |