Last updated: July 2, 2025
Understanding the UV Index is essential for residents and visitors in Boston, United States, as it plays a vital role in safeguarding your skin health and preventing sunburn. With a humid subtropical climate, Boston experiences varying UV levels throughout the day, peaking around noon when the UV Index can soar to a high of 11. Knowing these levels empowers you to take proactive measures—whether it’s applying sunscreen, wearing protective clothing, or seeking shade—ensuring you enjoy the beautiful Boston sun while minimizing the risk of skin damage. Stay informed and protect your skin!
The UV Index for today starts off mild, peaking at 1 by 7:00 AM, then gradually increases as the sun climbs higher in the sky. By 10:00 AM, it hits 6, indicating a moderate level of UV exposure. The intensity keeps climbing, reaching a maximum of 11 at 1:00 PM, making this the most crucial time for sun safety. As the afternoon progresses, the index begins to wane, dropping to 8 by 3:00 PM, then further to 2 by the evening, signalling a return to a safer UV environment. Remember, protecting your skin is vital during those peak hours of 10 AM to 2 PM!
| 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 | 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 |