Last updated: May 3, 2025
Understanding the UV Index in Ontonagon, United States is crucial for maintaining skin health and preventing sunburn, especially during the summer months when UV levels can peak significantly. With a humid continental climate (Dfb), Ontonagon experiences varied sunshine hours, which can lead to increased UV exposure. By being aware of daily UV levels, residents can take proactive measures to protect themselves from harmful effects, such as skin damage and increased cancer risk. As the UV Index rises to a maximum of 8 around midday, it’s essential to plan outdoor activities thoughtfully to stay safe in the sun.
As the sun rises, the UV Index begins its gradual ascent, starting at a mild 1 by 07:00. By 09:00, it nudges up to 2, marking the beginning of greater awareness for sun protection. The intensity peaks at 12:00, with a robust 7, leading to 13:00 and 14:00, where it reaches an impressive 8—the prime time for outdoor activities. As the afternoon light begins to wane, the index dips to 6 by 16:00, and further declines to 4 at 17:00. The evening cools down with a UV Index of 2 by 19:00, reminding us that while sun exposure is crucial for a sunny day, vigilance is key as we enjoy the longer hours of daylight.
| Time | UVI | Category | Time to Burn |
|---|---|---|---|
| 07:00 | 1 | low | 45 min |
| 08:00 | 1 | low | 45 min |
| 09:00 | 2 | low | 45 min |
| 10:00 | 3 | moderate | 30 min |
| 11:00 | 5 | moderate | 30 min |
| 12:00 | 7 | high | 25 min |
| 13:00 | 8 | very high | 15 min |
| 14:00 | 8 | very high | 15 min |
| 15:00 | 7 | high | 25 min |
| 16:00 | 6 | high | 25 min |
| 17:00 | 4 | moderate | 30 min |
| 18:00 | 3 | moderate | 30 min |
| 19:00 | 2 | low | 45 min |
Throughout the year, the UV Index experiences notable seasonal changes, with significant increases from late winter into summer. January sees a low UV Index of 2, indicating minimal risk, while February and March rise to 4 and 5, respectively, where exposure becomes moderate. April marks the onset of high-risk periods with a UV Index of 7, peaking in May and June at 8 and 9, categorized as very high. This trend continues into July and August, where protective measures are essential due to the same high values of 9 and 8. By September, the UV Index decreases to 7, signaling a return to high risk but gradually moderating through October (5) and November (3) before dropping back to low levels in December. Visitors and residents are strongly advised to prioritize sun protection during the months of May through September, when the potential for skin damage is greatest, using protective clothing, sunscreen, and seeking shade during peak hours.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Ontonagon | 2 | 4 | 5 | 7 | 8 | 9 | 9 | 8 | 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 |