Today will be hot and muggy like Wednesday, but temperatures should cool down as evening progresses and are expected to remain cool for next week, meteorologists say.
Wednesday was the official beginning of summer, and the heat wave was felt across the nation.
Though local temperatures only reached 94 degrees - 7 degrees short of the record - the 100-degree heat index made the temperatures feel much warmer.
"The heat index is sort of the apparent temperature," said Craig Evanego, meteorologist for the National Weather Service in State College.
"It's the number you get when you combine the actual temperature and the humidity - so the heat index is what it actually feels like outside," he added.
Multiple heat records were broken across the nation. All three New York City airports saw the mercury climb higher than ever before, and those in Philadelphia felt 97-degree temperatures - only one degree short of the city's 1931 record.
Even schools have been affected. According to national reports, Howell, N.J., school officials ended their school year a day early because of the heat.
Today's local heat index is expected to be around 100 again. Because of this, the weather service has issued a heat advisory until 8 p.m.
Locals, especially young children and the elderly, should stay inside as much as possible and drink lots of water to avoid dehydration. Those who must be outside should try to stay in the shade, hydrate and wear sun block.
"Drink a lot, and try to stay indoors during the hottest hours of the day - the middle of the morning to the early afternoon," Evanego said.
Locally, the heat over the last two days was caused by a ridge of high pressure that has hovered over eastern Pennsylvania.
"That high pressure created the heat and humidity, which resulted in the high heat index," Evanego said.
A cool front is supposed to move into the area this evening, bringing with it showers, possible thunderstorms and cooler temperatures, according to meteorologists.
Friday temperatures are supposed to hover around the low 80s.
"That may not sound like much of a drop, but with the lower temperatures and heat index, it's going to feel noticeably cooler as that front comes through," Evanego said.