UV Index in Boston, United States

Last updated: June 2, 2025

In Boston, United States, being aware of the UV Index is crucial for protecting your skin and overall health. The UV Index measures the strength of ultraviolet radiation, which can lead to sunburn and long-term skin damage if not monitored. Understanding these levels helps you take appropriate precautions, especially during the sunniest times of the day. Boston’s Dfb climate brings a mix of both chilly winters and warm summers, but even on milder days, UV exposure can reach concerning levels. For instance, peak UV Index values can hit 10 around noon, prompting the need for effective sun protection to prevent harmful effects. Stay informed and safeguard your skin as you enjoy all that Boston has to offer!

Hourly UV Index in Boston

As the sun rises, the UV Index gradually climbs, beginning at a mild 1 at 7:00 AM. By 9:00 AM, it reaches 3, prompting early risers to consider sun protection. The intensity peaks at 1:00 PM with a maximum of 10, signaling the most hazardous conditions for unprotected skin. As the afternoon unfolds, the index dips from 9 at 2:00 PM to 6 by 4:00 PM, offering a brief respite. As the day winds down, the UV rays decrease, falling to 2 by 6:00 PM and returning to a safe 1 by 7:00 PM. Stay mindful of these fluctuations to enjoy the sun while safeguarding your skin!

Average solar exposure data for the current time of the year. Actual values may vary and depend on many factors, such as cloud cover, vegetation cover, surface type, etc.
TimeUVICategoryTime to Burn
07:001low45 min
08:002low45 min
09:003moderate30 min
10:005moderate30 min
11:007high25 min
12:009very high15 min
13:0010very high15 min
14:009very high15 min
15:008very high15 min
16:006high25 min
17:004moderate30 min
18:002low45 min
19:001low45 min

Monthly UV Index Trends in Boston

Throughout the year, UV index levels fluctuate significantly, with notable increases during the warmer months. January and February experience a moderate UV index of 3 and 4, allowing for a 30-minute burn time under the sun. As the seasons transition into March and onward, the risk escalates, peaking in June and July with a maximum UV index of 10—classifying these months as high-risk. During these summer months, individuals are advised to limit sun exposure to just 15 minutes to prevent skin damage. The trend continues with August and September maintaining high levels (UV index of 9 and 8 respectively) before tapering off in October (UV index 6) and returning to moderate levels in November and December (UV index of 4 and 2). Residents and visitors should prioritize sun protection, especially during the peak months of April through September.

Monthly Maximum UV Index for Boston, United States

The monthly maximum UV Index (UVI) represents the highest UV radiation level recorded each month in Boston. It measures the strength of ultraviolet radiation from the sun and helps assess the risk of sunburn and UV-related health issues.
JanFebMarAprMayJunJulAugSepOctNovDec34689101098542
Data source: Statistical UV Index data for Boston, based on information from the Copernicus Climate Change Service.

UV Risk Categories

  •  Extreme (11+): Avoid the sun, stay in shade.
  •  Very High (8-10): Limit sun exposure.
  •  High (6-7): Use SPF 30+ and protective clothing.
  •  Moderate (3-5): Midday shade recommended.
  •  Low (0-2): No protection needed.

Compare Boston UV Index with Other United States Cities

The table above highlights how UV exposure in Boston compares to other major locations across United States. This comparison helps travelers and residents better understand regional sun intensity and plan outdoor activities with sun safety in mind.
Boston's solar exposure compared to other cities in United States. Generated using Copernicus Atmosphere Monitoring Service information.
 JanFebMarAprMayJunJulAugSepOctNovDec
Boston34689101098642
Chicago UVI34689101098642
Brooklyn UVI35681010998642
New York City UVI35681010998642
Los Angeles UVI46891011111010754
Houston UVI589111112121110975