Excessive heat hits N.C.

"It is insufferable out there," WRAL chief meteorologist Greg Fishel said.

Temperatures reached 100 degrees in Raleigh on Friday afternoon and the heat index hit 111 degrees. Seventy central and eastern counties are under either an excess heat warning or heat advisory.

All you need to know about living in the heat

"This is extremely dangerous, especially for young folks, the elderly," WRAL meteorologist Elizabeth Gardner said.

She explained that high humidity keeps perspiration from evaporating, preventing the body from cooling down. That leads to heat-related illnesses.

WakeMed’s Dr. Scott Fairbrother said symptoms of heat related illnesses include someone appearing confused or disoriented.

“If they have slurred speech; if they’re a little sluggish when they walk; if they look like they’re stumbling; if they’re not answering questions appropriately, that’s a big red flag,” he said.

Fairbrother said heat exhaustion can strike anyone outside in the heat for a long time or anyone working in the heat.

Since mid-June, nearly 500 people stricken with heat-related illnesses have been seen in emergency rooms, state officials said. Many of the patients were young and middle-aged adults.

Wake Emergency Services said they have not seen a significant increase in heat-related cases.

Emergency workers were on alert at the Raleigh Amphitheater on Friday where a concert was scheduled. Rescue workers said the key is preparing for the heat early by drinking plenty of fluids the day before.

At the Garner Police Leadership Academy, officers were letting rising high schoolers take no chances while running an obstacle and doing other outdoor activities.

"The heat is oppressive, and your body can only deal with so much of it. And the ways that you have to deal with that are take breaks, don’t exert yourself too frequently, and stay hydrated," said Chris Clayton, with the Garner Police Department.

"I think people, young people especially or people who are generally in good shape, forget sometimes that those rules apply to them too," he added.

In Durham, runners braved the heat at the Russell E. Blunt East Coast Invitational, a track meet held at Wallace Wade Stadium on Duke University's campus.

“My main concert is spectators and fans – the ones sitting in the stands. They may sit there and not hydrate themselves and drink water and those are the ones that pass out on us,” tournament director Frank Davis said.

Fort Bragg was under a Category 5 heat advisory - the highest level - on Friday. Because of the advisory, intense training was reserved for cooler hours of the day.

In Hope Mills, the local library had to close on Friday due to a malfunctioning air conditioner. It is not clear when the library will be able to reopen.

The heat wave won't get much better this weekend – and that brings more potential problems, Gardner said.

"We’ve got two, maybe three more days of this," she said. "Every consecutive day that we have this kind of heat, it becomes more and more dangerous. We see more and more people succumbing to heat-related injuries."

The mercury could jump to around 101 degrees both Saturday and Sunday, and high humidity will keep the heat index in dangerous levels. There's a small chance of a few late-day storms this weekend.