Last updated: June 2, 2025
Understanding the UV Index is essential for residents and visitors in Boston, United States, as it serves as a crucial indicator of sun exposure risk. With the potential for sunburn and long-term skin damage, being aware of UV levels can help you take protective measures to ensure skin health and overall well-being. Boston's humid subtropical climate means that during the summer months, UV radiation can reach concerning levels, peaking at a striking 10 around midday. By staying informed about the UV Index, you can enjoy the outdoors safely while minimizing the risks associated with overexposure to the sun.
The UV Index data unveils a dynamic progression of sun intensity throughout the day. Starting low at 1 at 07:00, the index gradually escalates, reaching maximum levels of 10 between 12:00 and 14:00. This peak signals a critical time for sun protection. As the afternoon wanes, the index tapers off to 8 at 15:00, and then descends further to 3 by 17:00, and 2 by 18:00. Ultimately, the day concludes softly with a return to 1 at 19:00. It's essential to stay vigilant during those peak hours to safeguard your skin while enjoying the sun!
| 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 | 10 | very high | 15 min |
| 14:00 | 10 | very high | 15 min |
| 15:00 | 8 | very high | 15 min |
| 16:00 | 6 | high | 25 min |
| 17:00 | 3 | moderate | 30 min |
| 18:00 | 2 | low | 45 min |
| 19:00 | 1 | low | 45 min |
Throughout the year, the UV Index experiences significant fluctuations, indicating varying levels of sun exposure risk. January and December see the lowest levels, with a moderate UV Index of 3, allowing for a burn time of 30 minutes. As spring approaches, March escalates to a high index of 7, reducing burn time to 25 minutes, while April and May peak at 9 and 10 respectively, categorizing them as very high risk months with burn times as low as 15 minutes. The intensity peaks in July at an extreme UV Index of 11, where just 10 minutes of exposure can lead to skin damage. Following summer, the risk remains high through August and September, before tapering into moderate levels in November. Residents and visitors should prioritize sun safety during March to October, taking precautions such as wearing sunscreen, protective clothing, and seeking shade during peak hours, especially in the summer months when the UV Index is at its highest.
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 |
| Boston | 3 | 5 | 7 | 9 | 10 | 10 | 11 | 10 | 8 | 7 | 5 | 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 |