Last updated: July 2, 2025
Understanding the UV Index is crucial for residents of Charlestown, United States, where the climate often leans towards warmth and humidity. With peak UV levels reaching 10 during the midday hours, it's essential to be aware of potential risks to your skin health, including the likelihood of sunburn and long-term damage. By tracking these daily UV levels, you can take proactive steps to protect yourself and your loved ones from harmful solar radiation. Amidst the allure of outdoor activities that Charlestown offers, staying informed about the UV Index will ensure you enjoy the sun safely and responsibly.
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 |
As the seasons change, so does the UV Index, which indicates the strength of ultraviolet radiation and the associated risk of harm from sun exposure. High-risk months for UV exposure typically occur from March through September, peaking in June with an extreme Index of 11 and a burn time of just 10 minutes. April and May are also notably hazardous, with very high UV ratings of 9 and 10 respectively. During these months, it is crucial for visitors and residents to take protective measures, such as wearing sunscreen, protective clothing, and seeking shade during peak hours. Conversely, during the winter months of January, November, and December, the UV Index is moderate, allowing for longer exposure times of up to 30 minutes without immediate risk. Always stay informed and prioritize sun safety to enjoy the outdoors responsibly throughout the year.
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 |
| Charlestown | 3 | 5 | 7 | 9 | 10 | 11 | 10 | 10 | 8 | 7 | 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 |