Last updated: July 2, 2025
In Williamstown, United States, understanding the UV Index is crucial for maintaining skin health and preventing sunburn. With a Cfa climate characterized by hot summers, residents and visitors alike face varying UV exposure risks throughout the day. As the UV Index climbs to a peak of 10 at noon and early afternoon, being aware of these levels allows you to take necessary precautions, ensuring enjoyable outdoor activities without compromising your skin’s well-being. Stay informed and protect yourself from the sun’s harmful rays!
As the sun rises, the UV Index begins its gentle climb, starting at a modest 1 at 7:00 AM and 8:00 AM. By 9:00 AM, it nudges up to a 2, signaling the day is warming up. However, the intensity ramps up dramatically around 10:00 AM, peaking at 9 by 12:00 PM. The highest alert comes at 1:00 PM and 2:00 PM with a striking 10, indicating it’s time to seek shade and protect your skin. As the afternoon unfolds, the index recedes slowly, dropping to 5 by 5:00 PM and settling down to a safe 1 by 7:00 PM. Keep in mind, during peak hours, the sun's rays are most potent—stay safe and enjoy the sunshine wisely!
| 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 | 4 | 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 | 1 | low | 45 min |
Throughout the year, UV exposure changes significantly, with high-risk months identified from April to September, when the UV Index reaches notably high levels of 9 to 10. During these months, burn times are critically reduced to just 15 minutes, requiring extra caution. March marks the transition to higher UV levels, with an index of 7 and a 25-minute burn time, while January and February begin with a moderate UV Index of 3 to 5 and longer burn times of 30 minutes. As we move into the fall, UV exposure decreases, dropping to 4 in November and 3 in December. Visitors and residents are advised to protect their skin by wearing sunscreen, protective clothing, and seeking shade, particularly during high-risk months, to minimize the risk of UV-related skin damage.
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 |
| Williamstown | 3 | 5 | 7 | 9 | 10 | 10 | 10 | 9 | 8 | 6 | 4 | 3 |
| 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 |