Tens of millions of Americans to swelter in triple-digit temps this week

Mother Nature has cranked up the furnace for the latter part of August as a massive heat dome stifles more than a dozen states with the hottest weather of the summer. AccuWeather meteorologists say that the wide area and the prolonged nature of the intense heat can put a significant strain on residents, animals and the energy grid.

Excessive heat warnings were in place for 19 states stretching from Texas and Louisiana to Minnesota and Ohio as of Thursday. AccuWeather RealFeel® Temperatures may soar to above 120 degrees Fahrenheit in part of this corridor during the peak heating of the afternoon. This level is considered "dangerous" on AccuWeather's exclusive RealFeel® temperature guide. On Monday afternoon, several towns in Kansas and Missouri reported RealFeel Temperatures over 130 degrees, with Oskaloosa, Kansas, topping out at 138 degrees.

With such a widespread area facing extreme temperatures, energy demand is going to be very stressed, according to AccuWeather Senior Meteorologist Alan Reppert.

AccuWeather meteorologists say that temperatures will challenge long-standing records on both sides of the clock amid the late-summer swelter.

Chicago just had its hottest day of the summer on Wednesday as temperatures peaked at 98 degrees. Temperatures also set a new record for the date. Farther to the north along Lake Michigan, Milwaukee hit the 100-degree mark, which blew away the prior season's high mark of 91, last reached on July 25.

The heat ramped up over the weekend across the South Central states, with Wichita, Kansas, hitting an eye-popping 111 on Saturday afternoon, falling just 3 degrees short of their all-time August record of 114.

Triple-digit readings will persist across this part of the nation's midsection through the rest of the week, while also expanding northward into the central Plains and Midwest, bringing the highest temperatures of the summer, according to AccuWeather Meteorologist Brandon Buckingham.

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Record high temperatures are expected to be challenged over consecutive days in places such as Minneapolis; Chicago; Des Moines, Iowa; Kansas City and St. Louis, Missouri; Little Rock, Arkansas; Dallas; and New Orleans; among dozens of other locales. Some of the record highs date back to a period of extreme heat in August of 1936. The Dust Bowl Era of the 1930s was one of the hottest decades on record in the central U.S.

A woman is silhouetted against the setting sun as triple-digit heat continues in the Midwest Sunday, Aug. 20, 2023, in Kansas City, Mo. (AP Photo/Charlie Riedel)

Historical average high temperatures are beginning a downward trend from their peak midsummer levels by this point in the month. This week, AccuWeather forecasters say that temperatures will consistently be 10-20 degrees above historical averages for late August.

The record heat can extend as far south and east as Atlanta and Mobile, Alabama, with temperatures in the middle 90s to lower 100s forecast into the weekend.

"As the core of the heat dome has remained largely in place over the South in recent weeks, the results have been truly exceptional in cities such as Austin, Texas," AccuWeather Meteorologist La Troy Thornton said. "Daily record highs have been either broken or tied on all but four days since Aug. 4 at Bergstrom International Airport."

AccuWeather meteorologists say that overnight temperatures are just as important to be aware of during patterns of extreme heat. This week, the setting sun will offer little in the way of relief from the stifling weather.

"The overnight hours, when temperatures are expected to drop to the daily minimum, can become a secret danger to residents during a heat wave," AccuWeather Meteorologist Alyssa Glenny said. "When the air temperatures remain at elevated levels as people go to sleep, additional strain to the heart can occur as the body tries to regulate the internal temperature."

Overnight lows will barely dip into the 70s, perhaps remaining in the lower 80s in some urban areas. Residents without proper means to sleep in an air-conditioned dwelling will be at a heightened risk of experiencing heat-related illnesses in the pattern.

In dozens of locales, records could be set for how high that the temperatures remain overnight.

"The temperature doesn't tell the whole story," AccuWeather Senior Meteorologist Bill Deger said.

High humidity levels accompanying the heat blast will make it harder for the body to cool properly when outdoors. The body's perspiration evaporates from the skin at a much slower rate in such conditions, making it more difficult for the body to shed excess heat.

AccuWeather experts urge residents and visitors across the region to avoid spending time outdoors during the peak heating of the day if at all possible. Plenty of water and electrolyte beverages should be consumed whether inside or outside to maintain proper hydration levels. Wellness checks are encouraged for individuals most at risk in high heat, such as the elderly and those without air conditioning. Pets and livestock should also be monitored for heat-related impacts.

A pattern change in the atmosphere will shift the core of the heat westward during the last weekend of August into early next week, AccuWeather meteorologists say.

Welcome cooling will arrive in time for the weekend across portions of the Midwest, including in Minneapolis and Chicago, with high temperatures dropping into the 70s and lower 80s behind a cold front.

Thunderstorms, some locally severe, will roll from the upper Great Lakes to parts of the Ohio Valley and the central Appalachians into Thursday.

Farther south, the cooling will not be quite as impressive, but temperatures will still drop to levels closer to the historical averages, offering some relief for heat-weary residents.

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