When is UV strongest in Boston?

Around June, when Boston's estimated clear-sky UV index peaks near 11 at solar noon. It is weakest around December, near 1. These are clear-sky estimates from the sun's angle and the city's elevation; clouds and ozone move the daily reading.

How fast can you get sunburned in Boston?

At the June clear-sky peak (UV 11), unprotected fair-to-medium skin (Fitzpatrick type III) can begin to burn in about 18 minutes, and the most sun-sensitive skin (type I) in about 12. In December (UV 1), midday UV stays below 3, where burn risk is minimal for most people.

Boston, Massachusetts UV Index

Boston UV index today — burn time, EPA scale, and sun-protection guidance

Boston, MA · UV Index right now

Sunburn risk Minimal

UV 0LowObserved 1:00 AM EDT

A UV index of 0 sits in the EPA Low band: sunburn risk is minimal for most people, and no sun protection is needed for the average person outdoors.

Peak UV today: 10:37 AM–2:37 PM

Estimated from today’s sunrise and sunset: UV is strongest in the two hours either side of solar noon (12:37 PM local time).

EPA UV Index scale

Low0–2

Moderate3–5

High6–7

Very High8–10

Extreme11+

Current reading: UV 0 — Low.

Sun protection right now

SPF & cover-up: No protection needed for most people. You can safely stay outside.
Reapply: Reapply every two hours and after swimming or heavy sweating.
Safe exposure: At UV below 3 there is no meaningful burn risk for most people. You can be outside without sunscreen, though sunglasses still protect your eyes.

EPA / WHO sun-safety guidance; type III skin baseline. Current band: Low.

Burn time by skin type

How fast unprotected skin can begin to redden depends on the UV index and your Fitzpatrick skin type. Below UV 3 (Low), burn risk is minimal for most people.

See the full minutes-to-burn table for every UV level and all six skin types in the sunburn-time guide.

UV through the year in Boston

This far north the sun sits low for much of the year, so UV in Boston is concentrated in the high-summer months and peaks in June, when the estimated clear-sky peak UV index reaches about 11 around solar noon. At that peak the noon sun reaches about 71° above the horizon. Each month below pairs the noon sun elevation with the estimated peak UV and how fast unprotected skin can begin to redden.

Noon sun elevation, estimated clear-sky peak UV, and burn time by skin type
Month	Noon sunelevation	Peak UVclear-sky est.	Type Imin to burn	Type IIImin to burn	Type VImin to burn
January	27°	2	—	—	—
February	35°	3	44	67	222
March	46°	6	22	33	111
April	57°	8	17	25	83
May	67°	10	13	20	67
June	71°	11	12	18	61
July	69°	11	12	18	61
August	62°	9	15	22	74
September	51°	7	19	29	95
October	39°	4	33	50	167
November	29°	2	—	—	—
December	24°	1	—	—	—

Clear-sky estimate from sun angle and elevation — day-to-day clouds and ozone shift the real index up or down. Burn times are first-redness approximations for unprotected skin, not a safe-exposure budget.

Frequently asked

When is UV strongest in Boston?: Around June, when Boston's estimated clear-sky UV index peaks near 11 at solar noon. It is weakest around December, near 1. These are clear-sky estimates from the sun's angle and the city's elevation; clouds and ozone move the daily reading.
How fast can you get sunburned in Boston?: At the June clear-sky peak (UV 11), unprotected fair-to-medium skin (Fitzpatrick type III) can begin to burn in about 18 minutes, and the most sun-sensitive skin (type I) in about 12. In December (UV 1), midday UV stays below 3, where burn risk is minimal for most people.

UV & sun-safety guides

See how the UV Index works — including why clouds are no shield — plus evergreen guides to burn time, vitamin D, skin-cancer risk, and when UV is strongest, collected on the UV Index hub.