Extreme heat warning for most of Massachusetts, Boston could hit 100 degrees Tuesday
The first heat wave of 2025 became official in Boston Tuesday morning when it reached 90 degrees in the city for the third consecutive day.
It's all part of a "heat dome" on the East Coast that could send temperatures to 100 degrees in Boston Tuesday. An extreme heat warning is in effect for much of Massachusetts.
What is a heat dome?
The term "heat dome" is just another way of saying a large area of high pressure. This promotes sinking, warming air over a large area and will lead to numerous record high temperatures being set as well as the first heat wave for many in the Northeast.
It's been about a year since we had a heat wave in the Boston area.
In fact, we had two in 2024, one in June and one in July, both of which lasted the minimum requirement of three days.
Boston hit it's second 90 degree day of the season on Sunday with a high of 94 degrees. It reached 90 Monday, and again at 9 a.m. on Tuesday. The forecasted high for Tuesday is 100 degrees.
Some towns away from the coast could hit a four-day heat wave with highs Wednesday in the 90s away from the coast.
Extreme heat warning
An extreme heat warning is in effect through Tuesday for the following Massachusetts counties: Suffolk, Plymouth, Bristol, Norfolk, Middlesex, Essex, Worcester, Franklin, Hampshire and Hampden.
Heat could set records in Massachusetts
We are forecasting the record of 95 degrees on Tuesday (set in 2013) to be shattered.
If we were to hit the century mark in Boston, it would only be the 28th time in recorded history and the first occurrence since 2022. It would also equal the all-time June record, set last in 2021.
It's possible that many of our suburbs will nick 100 Tuesday afternoon.
Wednesday currently looks to top out in the mid 80s, but we can't rule out that forecast changing.
We will see some "cooler" weather later in the week, likely along with a chance for thunderstorms.
If your occupation requires you to be outdoors and in the sunshine for long stretches of time, we urge you to be cautious the next few days.
When the heat indices reach near or over 100 degrees, heat stroke is a real concern.
Please be sure to check on those without air conditioning or ways to cool down. And of course, don't forget the pets - they get hot too.
