Mass., NH under extreme heat warning: Timeline for when temps peak, relief arrives

BOSTON — We’re on a WEATHER ALERT from the Boston 25 Weather Team due to an extreme heat warning across nearly all of Massachusetts and New Hampshire.

Extreme Heat Warnings in effect through Saturday PM to account for dangerous heat & humidity - it will feel closer to 115° at times! pic.twitter.com/i7T0sCM6Xc
— Vicki Graf (@VickiGrafWX) July 1, 2026

Boston Mayor Wu issues warning, activates cooling centers as triple-digit heat threat looms

This warning is in effect for the following Massachusetts counties from 10 a.m. Wednesday, July 1, through 8 p.m. on Saturday, July 4:

Franklin
Worcester
Middlesex
Essex
Hampshire
Hampden
Norfolk
Suffolk
Bristol
Plymouth

Boston 25 Meteorologist Vicki Graf urged Bay Staters to brace for “feels-like” temperatures possibly surging up to 115 degrees.

Dangerously hot conditions, with heat index values of 98 to 115 degrees, are expected during the warning period, with the worst of the heat and humidity on Thursday and Friday.

“This is a prolonged and dangerous heat wave with little relief at night,” the National Weather Service warned.

[Extreme Heat Warning Through Saturday] Extreme heat and humidity develops this afternoon and continues through Saturday. The worst of the heat peaks Thu and Fri when afternoon heat indices reach between 100 and 115 degrees! This will be a prolonged and dangerous heatwave! pic.twitter.com/uqEek02xlG
— NWS Boston (@NWSBoston) July 1, 2026

The only parts of Massachusetts that are not covered by the extreme heat warning are Northern Berkshire, Barnstable, and Dukes counties, where a heat advisory is in effect from 10 a.m. Wednesday through 8 p.m. Saturday.

Heat index values of 95 to 105 degrees are expected in those areas.

Come Sunday, temperatures in Massachusetts are expected to dip back down into the high 80s, with low 80s to start next week.

In New Hampshire, the following counties are under an extreme heat warning from 11 a.m. on Wednesday through 8 p.m. on Friday:

Northern Carroll
Southern Grafton
Southern Carroll
Sullivan
Merrimack
Belknap
Strafford
Cheshire
Eastern Hillsborough
Interior Rockingham
Coastal Rockingham
Western and Central Hillsborough

Heat index values of up to 111 degrees are expected in those areas. Like the Bay State, the worst of the heat and humidity in the Granite State is expected on Thursday and Friday.

High temperatures in New Hampshire won’t dip back into the 80s until Sunday.

Residents are reminded that heat-related illnesses increase significantly during extreme heat and high humidity events. Officials recommend drinking plenty of fluids, staying in an air-conditioned room, staying out of the sun, and checking up on relatives and neighbors.

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Shiri Spear|David Bagley|A.J. Mastrangelo|Vicki Graf

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