Boston broke a daily record high temperature Sunday and New York City and Philadelphia may follow suit as an "extremely oppressive" heat wave intensified in the Northeast, leading to at least two heat-related deaths over the weekend.

More than 85 million Americans faced excessive heat warnings and advisories Sunday from the Southern Plains to the Northeast, according to a National Weather Service statement.

In New York City, the city's medical examiner's office confirmed one person died as a result of heat exposure Saturday. The person had heart disease and emphysema, which contributed to the death, the medical examiner’s office said.

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In Pennsylvania, a 73-year-old man died from heat-related complications Thursday, NBC Philadelphia reported, amid a stretch of 90-plus degree days for the state. Philadelphia could approach 100 degrees Sunday, a forecasted temperature that would break the three-digit mark for the first time in a decade.

Is there relief in sight? A cold front approaching the Northeast on Monday and Tuesday should bring some less oppressive temperatures, according to the National Weather Service, but there is also the possibility of severe weather in the form of thunderstorms and high winds.

Tips to beat the heat:

Boston breaks daily heat record; New York City, Philadelphia could follow

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Boston hit a daily record high temperature of 99 on Sunday afternoon, breaking the previous record high of 98 set in 1933, according to the NWS. Providence, Rhode Island also broke its daily record Sunday, reaching a high of 96 and surpassing the previous record by two degrees.

New York City is forecasted to exceed its previous daily record of 97 degrees for July 24, first set in 2010, according to weather service meteorologist Marc Chenard. Philadelphia also has a forecasted temperature a degree above the city's daily records, Chenard told USA TODAY.

"Philly, New York City, Boston: all of those can be right around or just above the records for the date," he said.

Albany International Airport in New York's capital city already broke a daily heat record on Saturday, reaching 97 degrees and surpassing a daily record set in 1933, 1952 and 1955. 

Several major metros throughout the Northeast have put excessive heat measures into effect in attempt to keep residents cool. Philadelphia extended its heat health emergency declaration through Sunday, sending workers to check on those who are unhoused and other vulnerable residents.

A vendor selling ices crosses the street in midtown Manhattan as temperatures reach into the 90s on July 21, 2022 in New York City. Much of the East Coast is experiencing higher than usual temperatures as a heat wave moves through the area forcing residents into parks, pools and beaches to escape the heat.
© Spencer Platt, Getty ImagesA vendor selling ices crosses the street in midtown Manhattan as temperatures reach into the 90s on July 21, 2022 in New York City. Much of the East Coast is experiencing higher than usual temperatures as a heat wave moves through the area forcing residents into parks, pools and beaches to escape the heat.

Relief on the horizon for the Northeast

By Monday and Tuesday, an approaching cold front should help to cool down the high temperatures in the Great Lakes and the Northeast soon after, the National Weather Service predicts.

"As we head into the day tomorrow, it's kind of the transition day," Chenard said. "So it will still be warm to start, but then we'll actually see some thunderstorms during the day tomorrow, which should cool things off but also bring the threat of some severe weather to the region."

Residents in some cities can take advantage of cooling centers and other programs to stay safe, especially as the urban heat island effect exacerbates the hottest weather in urban areas.

New York City extended its public pool hours to 8 pm Sunday to help residents, and many libraries in Philadelphia are open as cooling centers during the city's heat health emergency.

While this week marks one of the most intense and long-lasting heat waves of the summer so far, the past six months weren't particularly mild overall. The first half of 2022 ranked the sixth warmest on record, according to the National Oceanic and Atmospheric Administration.

Contributing: The Associated Press

1 of 15 Photos in Gallery©Abbey Cutrer, The Tennessean / USA TODAY NETWORK

Jesse Minor wipes sweat from his forehead outside his shop Minor's Jewelry in Nashville, Tenn., Tuesday, June 14, 2022.

This article originally appeared on USA TODAY: 'Extremely oppressive' heat in Northeast turns deadly; Boston breaks record as other cities may follow