Massachusetts heat wave: How hot will it get in your area?

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DEDHAM, Mass. — A blistering heat wave has its grip on the region as sweltering heat and stifling humidity continue to cause for dangerous and uncomfortable conditions in Massachusetts on Wednesday.

Scorching temperatures in the mid to upper 90s are expected across the Bay State, including Boston and Worcester, where record highs could be tied or broken.

While summer doesn’t officially begin until Thursday, the temperatures on Wednesday will be some of the hottest Massachusetts sees all season, according to Boston 25 Meteorologist Shiri Spear.

The heat index in every community outside of southeastern Massachusetts will be more than 100 degrees.

The National Weather Service has issued a heat advisory for Northern Berkshire, Southern Berkshire, Western Franklin, Eastern Franklin, Northern Worcester, Central Middlesex County, Western Essex, Eastern Essex, Southern Worcester, Western Norfolk, Southeast Middlesex, Suffolk, Eastern Norfolk, Northern Bristol, Western Plymouth, Eastern Plymouth, and Northwest Middlesex counties.

An excessive heat warning has been issued for parts of New Hampshire, where heat index values of up to 105 degrees are expected.

“Take it easy in the extreme heat. Your body doesn’t cool down efficiently with the sweltering conditions,” Spear advised in her latest weather blog. “Heat-related illness, sunburns, and dehydration will be concerns with this first heat wave of the summer.”

An air quality alert has also been issued for Central Middlesex, Western Essex, Eastern Essex, Eastern Hampshire, Eastern Hampden, Southern Worcester, Western Norfolk, Southeast Middlesex, and Suffolk counties.

“Air is unhealthy for sensitive children and adults, such as those with asthma, lung or heart disease, and older adults,” the NWS warned. “Sensitive children and adults should limit prolonged outdoor activity.”

Air quality alerts are common on the hottest days of summer, Spear noted.

The heat is expected to break on Friday when a cold front will bring a chance for downpours and storms.

For more on the forecast, visit the Boston 25 Weather page.

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