Massachusetts braces for heat wave, record-setting temperatures possible in Boston

BOSTON – A heat wave is set to arrive in Massachusetts, and the WBZ Weather Team has issued a NEXT Weather Alert for the entire week ahead.

There is potential for this to be one of the hottest weeks in years and for several records to be shattered.

Where will it be hottest in New England?

The National Weather Service has issued an Excessive Heat Watch for areas just to the west of Boston including most of Middlesex County and southern New Hampshire.

These are the areas where the heat is expected to be at its absolute peak. Temperatures will be well into the 90s Tuesday through Friday, and it will feel like 105 degrees or higher at times.

Areas of relief

This certainly isn’t to say it won’t be very hot and humid outside of those areas.  

Temperatures will be in the 90s with heat indices near or over 100 in most of southern New England Tuesday through Friday and therefore the National Weather Service has issued a Heat Advisory for much of the remainder of the area.

The only relief will be found along the South Coast, Cape and Islands where a persistent, south-southwest wind will bring in some natural air conditioning.

There may be some occasional cooling over Cape Ann and other Coastal areas with intermittent sea breezes.

Highly rare “extreme” heat risk

NOAA’s heat risk outlook has highlighted parts of New England with an “extreme” risk. This is highly rare for our area.

It is defined as “the level of rare and/or long-duration extreme heat with little to no overnight relief … affects anyone without effective cooling and/or adequate hydration. Impacts likely in most health systems, heat-sensitive industries and infrastructure.”

How hot will it be in Boston?

During this heatwave, temperatures will remain quite warm during the overnights, thus not allowing much relief at all.

In the city of Boston, where heat typically remains trapped more readily, overnight lows will remain in the mid to upper 70s for several days, nearing record high minimums.

Speaking of records, Boston will also be near several high temperature marks this week. Don’t rule out hitting the century mark in and around the city and specifically in the Merrimack Valley and western suburbs.

Temperatures may set records

We will challenge some all-time June record highs in the major southern New England cities.

The highest temperature ever recorded in Boston in June is 100 degrees, on three occasions including in 2021.

The most uncomfortable days will be Wednesday and Thursday. It will feel like 100-110 degrees in most of the area during those afternoons.

This is just about as hot and extreme as it gets here.

Staying safe during extreme heat

It will be vitally important that those without adequate cooling are monitored for signs of heat exhaustion and heat stroke.

During the peak heat and humidity this week, everyone should try to limit their time spent outdoors, especially in full sunshine.

And, of course, don’t forget your pets. Certainly, do not leave them in the car. With an outdoor temperature of 90 degrees, temperatures inside the car rise very rapidly.

When will temperatures drop?

This massive “heat dome” over the eastern United States will start to break down later this week.

It appears as though cooler temperatures will arrive next weekend, along with some showers and thunderstorms.

Stay with the WBZ Weather team all week long. We will provide frequent updates on WBZ-TV, CBS News Boston and WBZ.com.