MUCH OF USA IN THE OVEN

Heat index rockets beyond 100 degrees in several cities

Searing heat continued its stifling march across much of the nation Monday. New York City opened more than 500 “cooling centers” to combat a heat index in excess of 100 degrees.

National Weather Service spokesman Chris Vaccaro said a heat advisory was in effect for the Southern Plains, East and Southeast. As of midafternoon, more than 53 million people were un- der a heat advisory, all the way from Oklahoma to New York City, the Weather Channel reported.

The heat index is a measure of how hot it feels when the humidity is factored in. Heat indexes of at least 100 were reported across most of the southeastern USA.

Arkadelphia, Ark., appeared to have notched the day’s record: a high temperature of 100 degrees and a heat index of 110, according to the weather service.

Georgia emergency officials tweeted out tips for staying cool — wear loose clothing, drink plenty of water and stay inside.

South Carolina’s Grand Strand beaches braced for a heat index that could reach 109 degrees Fahrenheit.

New York’s heat problems were compounded by a request from Consolidated Edison that 138,000 customers in Queens and Brooklyn conserve energy while the power company repaired equipment servicing the area.

Mayor Bill de Blasio asked residents and businesses across the city to set thermostats to 78 degrees to conserve energy.

De Blasio asked residents to check on seniors and others who might not be properly prepared for the heat.

“New Yorkers always look out for their neighbors, and this is a moment when we really need people to,” he said.

Baltimore and Washington also faced a second day of withering heat. Temperatures in the mid- to upper- 90s pushed the heat index over 100 in the afternoon in Washington, while Baltimore hovered near the mark.

The National Weather Service’s Vaccaro said the unrelenting heat should ease up in a couple days.

“This is typical of mid- late July,” he said. “In many places we aren’t seeing records, but it’s real hot and real humid. That can be dangerous.”

“New Yorkers always look out for their neighbors, and this is a moment when we really need people to.” NYC Mayor Bill de Blasio

LIZ DUFOUR, THE CINCINNATI ENQUIRER

DAVE SCHERBENCO, AP Top: Cooper Clare, 4, and his brother Chase, 3, cool off in Cincinnati. Above: Ricardo Reyes runs through the Coal Street Park Splash Pads in Wilkes Barre, Pa., on Sunday.