UV Index in Boston, United States

Last updated: June 2, 2025

Understanding the UV Index is crucial for residents of Boston, where the combination of sun exposure and the city’s humid continental climate can lead to significant risks for skin health. With UV levels peaking as high as 10 during midday hours, awareness of these fluctuations is essential to prevent sunburn and long-term skin damage. During the warmer months, when Boston boasts bright sunny days, being informed about the UV Index empowers locals and visitors alike to take proactive measures against harmful effects of ultraviolet radiation. Stay aware, stay safe, and enjoy the beauty of Boston’s summers while protecting your skin!

Hourly UV Index in Boston

The UV index begins its ascent at 07:00, starting at a gentle 1, then climbs gradually through the morning. By 10:00, it reaches a moderate 5, but from 11:00 onwards, the sun's intensity becomes pronounced, peaking at an impressive 10 between 13:00 and 14:00. After this zenith, the index dips to 8 at 15:00 and continues its decline, settling back to 2 by 18:00. As the day winds down into the evening, the UV index drops to a low 1 by 19:00, signaling a return to safer sun exposure levels. Enjoy the sunshine while staying protected during the high points!

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
14:0010very 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, the UV Index experiences notable fluctuations, indicating varying levels of sun exposure risk. The high-risk months occur from March to September, peaking in May and June with a UV Index of 10, classified as very high. This signifies a decrease in safe sun exposure time to just 15 minutes. In contrast, the lower UV Index months are January (3) and December (2), categorized as moderate and low, with burn times of 30 and 45 minutes, respectively. Residents and visitors are advised to take protective measures such as wearing sunscreen, protective clothing, and seeking shade, especially during the summer months when UV levels are at their highest. It is essential to stay informed and adjust sun exposure accordingly to minimize the risk of skin damage.

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.
JanFebMarAprMayJunJulAugSepOctNovDec357910101098642
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
Chicago UVI34689101098642
Brooklyn UVI35681010998642
New York City UVI35681010998642
Boston357910101098642
Los Angeles UVI46891011111010754
Houston UVI589111112121110975