Last updated: June 2, 2025
Understanding the UV Index is crucial for residents of Mason City, as this key metric helps to protect your skin health and prevent painful sunburns. With a climate characterized by hot summers and significant UV exposure—especially around midday when levels peak at 11—being informed about UV levels can empower you to take proactive measures, such as applying sunscreen or seeking shade. As you enjoy the sunny days in Mason City, remember that prioritizing UV awareness is essential for maintaining a healthy outdoor lifestyle.
The UV Index throughout the day follows a predictable rise and fall, peaking at 11 around 1:00 PM. Starting at a modest 1 at 7:00 AM, it gradually escalates, reaching 10 by 12:00 PM, signaling the need for sun protection. As the afternoon progresses, the index dips from 11 to 8 by 3:00 PM, then declines further to 2 by 6:00 PM, and finally settles back at 1 by 7:00 PM. This data underscores the importance of taking precautions during the hours of peak UV exposure, particularly between 11:00 AM and 3:00 PM, when levels are highest and pose the greatest risk to skin health.
| 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 | 11 | extreme | 10 min |
| 14:00 | 10 | 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 demonstrates significant seasonal fluctuations, with high-risk months typically occurring from April to September. In April, the UV Index escalates to 8, indicating very high exposure risks, and remains elevated through May (9) and June (11), where it reaches an extreme level. July (10) and August (9) continue to present very high risks, before tapering off in September (8). As a precaution, visitors and residents should take protective measures, especially during these peak months, by seeking shade, wearing protective clothing, and applying sunscreen frequently. In contrast, the UV Index drops to a moderate level (3-5) from October to March, allowing for safer outdoor activities during this period.
UV Risk Categories
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Mason City | 3 | 5 | 5 | 8 | 9 | 11 | 10 | 9 | 8 | 5 | 3 | 3 |
| 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 |