Summertime heat returning with a vengeance in the Midwest, will help spark severe storms

Midwesterners will be trading fall sweaters for summer shorts early this week, as temperatures soar in the region. AccuWeather meteorologists are also monitoring the risk for summertime thunderstorms.

This just in: it's still summer, and Mother Nature will be making that clear in the Midwest through the early part of this week, as AccuWeather meteorologists warn that temperatures will soar well into the 90s and even triple-digit territory in some areas over the next few days.

The heat, which will be accompanied by high humidity and result in AccuWeather RealFeel® Temperatures well over 100 for millions, can turn dangerous for those trying to enjoy some time outside as summer begins to wind down. It will also help fuel rounds of powerful thunderstorms that will traverse the edge of the hottest weather through midweek.

A drastic change from last week

The extreme heat that toppled all-time temperature records in Texas last week, and began to expand north through the Plains to start the weekend, will arrive in the north-central U.S. to end the weekend and start the week. The difference between this heat and the weather experienced for the past week will be nothing short of drastic, say AccuWeather meteorologists.

Temperatures that had been in the 70s during the day last week, will be replaced by highs in the 90s to around 100. At night, crisp temperatures in the 40s and 50s will be swapped out for sultry lows in the 70s.

For some, it may end be the hottest weather of the entire summer. In Des Moines, Iowa, the highest temperature recorded thus far this season was 98, back in late June. The AccuWeather Forecast for the capital of Iowa is a scorching 99 on Monday.

The mercury alone won't tell the whole story, as high humidity will push the RealFeel® Temperature—how it really feels to exposed skin outdoors—to as much as 15 degrees above the actual thermometer reading.

While an influx in moisture from the south explains some of the rise in humidity and thus RealFeel® Temperature, some of the increase is localized in nature, as the massive corn crop in the region produces moisture which is then transferred to the atmosphere in a process called evapotranspiration.

Ahead of the worst of the heat, heat advisories and warnings have gone up across a wide swath of the nation's midsection. Chicago, Kansas City, Milwaukee, Minneapolis and Omaha are among the major metropolitan areas under these alerts.

Some of, but not the core of the heat will also expand toward the East Coast later in the week, where a "false fall" was also enjoyed last week.

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For those ready for more of the fall preview that the Midwest experienced last week, there's good news in the extended forecast. The first of two cold fronts will knock the temperature and humidity back below excessively high levels from Tuesday into Wednesday, while a second front expected to pass through next weekend will prove the death knell—for now—to the summertime weather as the calendar turns from August to September.

Severe thunderstorms on the edge of the heat

Another hazard is in the forecast for the North Central states this week besides the heat: severe thunderstorms. AccuWeather meteorologists say that these storms will be found near the border of the extreme heat and cooler air to the north, and that they can pack a punch.

After an initial risk for severe storms into Sunday night in the Northern Plains, AccuWeather meteorologists say the threat will increase on Monday farther downstream.

"Several dangerous complexes of thunderstorms can develop and race eastward across South Dakota into southern Minnesota beginning later Monday," said AccuWeather Senior Meteorologist Dan Pydynowski. "Travel on portions of Interstates 35, 90 and 94 can be greatly impacted with downpours that can reduce visibility, along with the threats of large hail and damaging winds."

After enduring an afternoon of triple-digit RealFeel® Temperatures, thunderstorms are expected to roll into the Twin Cities of Minneapolis and St. Paul, Minnesota, on Monday night.

"Depending on the exact timing of the storms, the baseball game scheduled Monday evening between the Twins and Braves could be impacted or delayed by downpours and dangerous lightning," added Pydynowski.

The severe weather risk will accompany and precede the week's first cold front, which will arrive in the Great Lakes region on Tuesday and Wednesday. Millions more farther east, including in the cities of Buffalo, Cleveland and Detroit will be at risk of a dangerous storm or two closer to midweek.

A secondary threat for severe weather can occur late in the week, beginning as early as Wednesday in the Northern Plains, as the second cold front moves through.

Pydynowski has a few tips on how to stay prepared for and ahead of the storms. "Download the AccuWeather App, keep your phone charged and enable alerts as these storms can move through at night in many areas, adding an extra layer of danger," he said.

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