South, East baking in humid heat

Nearly half the country’s population sweltered under essentially triple-digit temperatures, as brutal heat and humidity afflicted a vast swath of the nation from New England to Texas.

At least 15 states were under heat warnings Tuesday.

The heat advisories — issued when the combination of temperature and humidity makes the perceived temperature more than 100 degrees — covered areas where 150 million people live, representing nearly half the nation’s 310 million people, said Eli Jacks of the National Weather Service.

He attributed the sweltering temperatures to a dome of high pressure that is sucking moist air from the Gulf of Mexico and dragging it across the eastern and central part of the country.

“It’s a combination of heat and humidity,” Jacks said. “Yeah, it’s summer. For the next two weeks or so there’s going to be a lot of heat around.”

In Oklahoma City, a rainstorm took temperatures slightly below 100 degrees for the first time since June 29. But triple-digit temperatures are expected to resume Wednesday and last for at least 10 days. The city has begun water rationing.

The Sooner State is used to blistering, 100-plus temperatures — but in August.

“We’re thinking, ‘Oh my gosh, we still have the rest of July and August to deal with,’ ” said Oklahoma City spokeswoman Kristy Yager.

The National Weather Service warned people to wear wide-brimmed hats and sunscreen and to take other precautions against the sun and searing temperatures. Jacks warned that cars could quickly heat up to a lethal 120 degrees and to be sure that pets and children are not left inside them.

In New York, the mercury hovered just below a record 99 degrees. Mayor Michael R. Bloomberg ordered shelters and senior centers to open their doors to anyone who needed a dose of air-conditioning and urged residents to check on neighbors.

“It’d be a good time to maybe stop in on somebody in your neighborhood who is elderly or maybe infirm and just knock on the door and say, ‘Are you drinking some water? I’m going to the store. Can I bring something back?’ ” he said.

In Chicago, temperatures dropped to the mid-80s, but more than 300,000 people were still without power after a ferocious storm Monday battered the electrical grid and briefly closed the city’s busy airports.

The heat wave rippled through the nation’s poultry belt, searing henhouses and farms from North Carolina to Arkansas and killing tens of thousands of chickens and turkeys. The Associated Press reported that one couple in Kansas lost 4,300 turkeys and took 26 hours to bury them.

In Kansas City, Mo., health officials were investigating whether two deaths were related to the combination of 100-degree temperatures and sweltering humidity. Amanda Waters of the local Salvation Army said volunteers were traveling the town handing out water and Gatorade to the homeless and those who had to labor outside, such as construction workers.

Dozens of people had sought refuge at air-conditioned shelters, Waters said. To locals, though, she added, it’s just a typical summer.

“In the Midwest,” she said, “we’re used to all types of weather.”

nicholas.riccardi@latimes.com