Triple-digit heat strikes again: Late summer heat to scorch millions

Could this be summer's last hurrah?

A short-lived but intense blast of heat is scorching portions of the Midwest and Northeast on Wednesday, one that's sending temperatures to "hazardous" levels in cities such as New York, St. Louis and Philadelphia.

For some folks, it may be the hottest weather of the entire summer, AccuWeather said , as temperatures top out in the upper 90s to the low 100s with the heat index.

The heat is affecting tens of millions of people Wednesday: As of Wednesday morning, heat alerts were in effect for nearly 50 million people in the Midwest and Northeast. And the nation's capital was bracing for temperatures over 100 degrees.

Highs around 100 were also expected in Tennessee, Mississippi, Southern California and Arizona.

The worst of the Midwest and Northeast heat should end by Thursday, forecasters said.

Meanwhile, the first snowflakes of the season were forecast to reach the higher elevations of northwestern Montana on Wednesday, the National Weather Service said. A winter weather advisory was in place for the mountains of northwestern Montana, where up to 10 inches of snow was possible.

The weather service warned people who planned to spend time outdoors in Montana to beware of hypothermia.

Hazardous heat

The magnitude of the extreme heat in the Midwest and Northeast, combined with oppressive warmth at night, will lead to hazardous conditions, particularly for the elderly and those with pre-existing health conditions, the weather service said.

Residents also were reminded to drink plenty of fluids, stay in an air-conditioned room, and stay out of the sun.

And importantly, people were warned to not leave children and pets in unattended vehicles. Car interiors can reach lethal temperatures in a matter of minutes, the weather service said.

Short-lived heat

The spell of record heat will be relatively short-lived as a cool high-pressure system settling into southern Canada is forecast to send a cool and damp air mass into the Great Lakes on Wednesday. It will quickly spread into New England on Wednesday night and reach into the mid-Atlantic by Thursday morning behind a sharp cold front.

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A second cold front that was expected to pass through by the weekend will prove the death knell – for now – to the summertime weather as the calendar turns from August to September, according to Bill Deger, AccuWeather senior meteorologist.

This article originally appeared on USA TODAY: Triple-digit heat strikes again: Late summer heat to scorch millions