Relief in Sight for U.S. Heatwave

U.S.|Extreme temperatures continue to envelop the U.S., but some relief is in sight.

• Aug. 13, 2021, 4:56 a.m. ET

If the forecasters are right, the extreme heat that has scorched much of the United States this week is now, thankfully, on its way out in hard-hit places like the Northeast and the Pacific Northwest.

Not that you’d be able to tell on Friday, though.

In Portland, Ore., it is expected to reach 101 degrees on Friday. Philadelphia could see a rare Aug. 13 high of 98. In New York City, the heat index value — which combines the air temperature with humidity to provide a number for what the air actually feels like — is forecast to soar as high as 105.

The dayslong stretch of harsh temperatures peaked in many parts of the country on Thursday. In the Pacific Northwest, still reeling from a June heat wave that was linked to hundreds of deaths, people fled to cooling centers to escape highs in the triple-digits. In Washington, D.C., temperatures climbed to 96 degrees, in Baltimore, the thermometer hit 98.

And Thursday night offered little respite from the day’s extremes, with metro areas across the Northeast and Mid-Atlantic enduring temperatures in the high 70s throughout the night.

“We’re not seeing tons of record highs being broken, but it’s the fact that those temperatures are not dropping,” said William Churchill, a meteorologist with the National Weather Service, explaining that the lack of a chance to cool off at night heightens the risk of heat-related illness, especially for people without access to air-conditioning.

Intense humidity across many areas experiencing extreme temperatures is only compounding those risks.

“When you have that high humidity, your sweat can’t do what it’s supposed to do which is evaporate and cool you down,” Mr. Churchill said.

More than 75 million people remained under some form of heat alert across the country on Friday, down from more than 200 million earlier in the week.

Cooler weather is expected over the weekend. And temperatures are expected to hover closer to normal in much of the country in the next couple of weeks, according to Brian Hurley, a meteorologist at the National Weather Service.

But, he said, projections show that above normal temperatures into September and October are likely.

“The pattern that we’re in, we could certainly see additional heat building up,” Mr. Hurley said.