A massive heat wave has more than two-thirds of the nation sweating and headed for cool air.

Temperatures are in the high 90s from the Midwest to the East Coast, and heat indices are even higher.

Meteorologists say the peak of the heat wave for major cities in the Northeast will hit Friday.

The heat index in Washington, D.C., is expected to reach 115 degrees. Philadelphia will have similar temperatures -- edging the cities closer to record-breaking heat.

"Honestly, it makes me not want to go out to lunch," Washington resident Katie Deekle said. "It makes me want to stay inside the air conditioning."

The busy lunch-rush in the nation's capital Thursday was all about frozen yogurt, as office workers ventured out of their air conditioned buildings in search of a sweet, cool treat.

"They come in sweaty," said Kevin Greezey, owner of FroZenYo. "We make sure we crank the a/c, and they feel great and get some frozen yogurt and they're on their way."

Still, frozen yogurt can't do it all.

Doctors and emergency officials are reminding the public to stay inside where it's cool, stay hydrated, and check on elderly friends, family, and neighbors to make sure they're okay.

Meteorologists warned that the recent hot spell, which has already claimed as many as 22 lives in the Midwest, could be worse than the 1995 heat wave that led to 750 deaths in Chicago alone.