More Than Half of U.S. States Broil in Deadly Heat Wave

U.S. weather experts Friday issued heat alerts for more than half of the 50 states as a blanket of hot air and humidity smothered the country, from Texas in the south to Maine in the northeast.

"We've put out a forecast including heat alerts, advisories and excessive heat warnings for all or part of 29 states and DC, from northern Texas to Maine," National Weather Service spokesman Chris Vaccaro told AFP.

The U.S. capital could again swelter under record high temperatures of more than 100 degrees Fahrenheit (37 Celsius), and feel even hotter than Death Valley in California, he warned.

"The forecast for Washington DC is supposed to be 103 -- that's the air temperature. It's 91 now in DC but it feels like 104, and this is at 9 o'clock in the morning. So it's shaping up to be a really hot day," Vaccaro said.

"DC might feel hotter than Death Valley, where the air temperature was 115 Fahrenheit at 9 o'clock in the morning.

"But with the humidity in DC, it could feel like we're between 115 and 120," (46-49 degrees Celsius), he said.

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Even normally cooler northern states were not spared from the punishing heat which has reportedly claimed 22 lives across the country in the past week.

"Right now, in Portland, Maine, it's 89 degrees (32 Celsius) and it feels like 100," or 38 degrees Celsius, Vaccaro said. "They're not used to that up there."

The triple-digit Fahrenheit heat will continue to impact a large swathe of the United States, with "bullseyes of high heat and humidity" in the central states and up and down most of the east coast.

It's the combination of heat and humidity that makes the heatwave so unbearable and potentially dangerous: the more moisture there is in the hot air, the more difficult it is for the body to sweat and cool itself.

In Washington and nearby Maryland, summer camps canceled outdoor activities to avoid children feeling the ill effects of the heat.

The Hidden Spring camp run by Montgomery County Parks and Recreation Service in Maryland for kids up to the age of 14, called off a scheduled hike to a waterfall, and took the 45 campers bowling instead.

"We don't have any indoor facilities, and with the heat today, it didn't seem wise to take the kids hiking. So an air-conditioned bowling alley seemed a good trade-off," camp director Eric Fishman told AFP.

In New York City, the Office of Emergency Management opened cooling centers in air-conditioned public facilities for people "experiencing physical discomfort in the heat wave."

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In Washington, swimming pools would remain open until late in the evening, John Stokes of DC Parks and Recreation said.

Summers on the east coast of the United States are known for their high temperatures and humidity, especially in the southern states.

But Vaccaro said the current heatwave has "a lot of unique and dangerous characteristics.

"It's extremely long-lasting, for a start. This latest surge formed a week ago, hitting the central states and then moving eastward. And we had another heatwave before that," he said.

The scale of the heatwave was also significant, said Vaccaro. As many as 34 states at a time have been under heat advisories during the bout of hot weather, which finally began lifting on Thursday in the Midwest.

The high temperatures on the east coast are expected to ease on Saturday, when a cold front -- or less-hot front -- moves through.

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Chicago felt some relief on Friday, after four days of debilitating heat.

Morning broke Friday in Chicago with temperatures in the low 80s (26-28 Celsius), but weather forecasters warned that the respite could be brief as a powerful wave of thunderstorms is expected to push through the region, reigniting the heat and elevating humidity levels.