The U.S. National Weather Service extended Friday its high-temperature alerts to 30 states. The heat wave has already taken 24 lives.

The NWS also issued a code-red air quality warning, which means that staying outdoors for any length of time is dangerous, especially for seniors, children, heart patients and people with breathing problems.

Friday promised to be an extremely hot day in several states on the East Coast, according to the NWS, and if high temperatures are accompanied by high humidity, the heat index could reach 46 C (115 F) before easing to 33 C (91 F) by late in the weekend.

In New Jersey, local authorities said that some 100 people, mostly teenagers, fainted from the heat in Camden, where more than 12,000 people gathered for a rock concert.

In Raleigh, North Carolina, the thermometer hit 38.8 C (102 F) on Thursday, tying a record set in 1952, while the heat index was 42.2 C (108 F).

The first death related to the heat wave occurred in Kansas City, and authorities have reported another 13 heat-related deaths in Missouri, including two women over 70.

In Fountain Prairie, Wisconsin, a 65-year-old man with health problems died of the heat.