UV Index in Boston, United States

Last updated: May 3, 2025

Understanding the UV Index is crucial for residents in Boston, Massachusetts, especially during the sunniest months when UV radiation can spike, reaching levels as high as 9 around midday. Awareness of UV levels is essential not only for preventing sunburn but also for safeguarding your skin's long-term health. Boston's Dfb climate presents unique challenges, with varying sun exposure risks throughout the year; you might be surprised how quickly UV levels climb even on overcast days. By keeping an eye on the UV Index, you can enjoy the outdoors while protecting your skin and promoting overall wellness.

Hourly UV Index in Boston

The UV Index data reveals a dramatic rise in solar intensity as the day progresses, peaking at 9 between 12:00 PM and 2:00 PM. Beginning with a mild 1 at 7:00 AM, it escalates steadily to 3 by 9:00 AM and hits 5 at 10:00 AM. As the sun climbs higher, caution is advised with a 7 at 11:00 AM before reaching that intense 9 during midday. The intensity then begins to taper off, dropping to 7 at 3:00 PM and gradually decreasing to 4 by 5:00 PM. The evening brings relief as the index falls back to 2 by 6:00 PM, and finally settles at 1 by 7:00 PM. This data highlights the importance of sun safety measures, particularly during the peak hours!

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
13:009very high15 min
14:009very high15 min
15:007high25 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