"The massive high pressure area responsible for the dangerous and relentless heat from the Midwest to the South will soon shift its position enough to allow a breath of fresh air to roll in from central Canada," said Accuweather.com expert senior meteorologist Alex Sosnowski. "The core of the heat will settle farther west."
New York City and Philadelphia are expected to remain hot Sunday, although not quite as oppressive, according to Accuweather.com, with high temperatures in the lower 90s.
The blistering heat wave that affected much of the eastern two-thirds of the nation with triple-digit temperatures has tied or broken nearly 3,400 maximum and minimum temperature records across the country in July, according to the National Oceanic and Atmospheric Association.
More than two dozen people have died, including a four-month old Indiana girl who police say was left in a car outside her home in Greenfield, about 25 miles east of Indianapolis, for an extended period of time when temperatures were above 100 degrees (38 C).
Severe weather, including thunderstorms and damaging winds, are likely to accompany the cooler temperatures, forecasters said. Cities that could see thunderstorms Sunday include Baltimore and Washington, D.C.
The cool-off will be slower in the mid-Atlantic because the cold front from Canada moving slowly south, according to Accuweather.
High temperatures Sunday are still expected to top 100 degrees in Raleigh, North Carolina, and Richmond, Virginia.
Power outages continue to plague more than 150,000 customers, primarily in West Virginia. About 31,000 AEP Ohio customers remained without power as of Saturday evening, along with 3,000 Toledo Edison customers.
In West Virginia, where some people have been without power since violent storms hit more than a week ago, Appalachian Power said on its website that nearly 63,000 customers were still without electricity as of Saturday evening, along with over 20,500 customers in Virginia.
There were still 34,000 homes and businesses without power in FirstEnergy's West Virginia territory.
(Reporting By Mary Wisniewski in Chicago, Scott DiSavino in New York and Kim Palmer in Cleveland; Editing by Bill Trott)