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Millions set to swelter as intense heat builds for summer solstice

© iStock - MarianVejcik
Mary Gilbert, AccuWeather meteorologist

Residents across the central United States have barely had time to cool down after days of brutal heat smashed records across a wide swath of the country. Now, AccuWeather forecasters say Mother Nature is set to crank up the thermostat to dangerous levels once again.

A northward bulge in the jet stream will keep sizzling heat centered over much of the Plains and portions of the Mississippi River Valley to end the weekend. This setup is sometimes referred to as a heat dome.

Sunday, much of the Dakotas and portions of Minnesota and Nebraska had temperatures soar into the upper 90s F and low 100s F. For the Dakotas and northern Minnesota, temperatures of this level are a staggering 15-25 degrees F above normal for the middle of June.

The mercury in Grand Forks, North Dakota, reached 100 degrees, breaking Sunday's high temperature record of 96 F set back in 1995. The city typically records a high temperature of 77 F in mid-June.

Forecasters say the dome of heat will shift eastward into the early week and bring a new push of uncomfortable air to millions of additional residents.

Uncomfortable heat will arrive by Monday for a large swath of the country. Areas from the Great Lakes, through the Mississippi River Valley and into the Plains and portions of the Southeast will start to swelter once again to start the week. 

Temperatures in cities like Chicago and St. Louis will soar well above-normal levels on Monday. Many locations will top out at temperature levels 5-15 degrees above normal for the last full day of astronomical spring. 

Heat will build in both intensity and areal coverage by Tuesday, the day of the 2022 summer solsice. The summer solstice will begin on Tuesday at 5:13 a.m. EDT/4:13 a.m. CDT and marks the first official day of astronomical summer.

"Chicago will record high temperatures in the low to mid-90s F on Monday and may challenge triple digits on Tuesday," AccuWeather Senior Meteorologist Dan Pydynowski said. 

By Tuesday, tens of millions of residents from the Plains, through the Midwest and into the Southeast will bake under intense and potentially dangerous heat.

"At first, while heat makes a return on Monday, humidity levels will stay in check," Pydynowski said. "However, conditions will become truly uncomfortable by Tuesday as humidity levels build."

With increased humidity levels and the most intense sunshine of the year courtesy of the summer solstice, AccuWeather RealFeel® Temperatures will soar several degrees above the actual air temperature on Tuesday. 

In places like St. Louis, AccuWeather RealFeel® Temperatures could climb into the middle 100s during the peak of afternoon heating on Tuesday, Pydynowski noted.

"Residents who can will want to make plans to stay indoors in air conditioning whenever possible or drink plenty of water if they have to be out in the heat," Pydynowski cautioned. 

Especially during the hottest part of the day, anyone who must be out and about is urged to monitor for signs of heat-related illnesses like heat exhaustion or heat stroke

Temperatures inside parked cars and other vehicles will also rise to dangerous levels early this upcoming week amidst searing heat and intense sunshine. Travelers are urged to never leave children or pets inside unattended vehicles as temperatures can climb to deadly levels in mere minutes. 

On average in the U.S., 38 children under the age of 15 die each year from heatstroke after being left in a vehicle, according to the National Safety Council

While the heat early this week is set to be intense for many, forecasters say the duration of the worst heat will be much shorter when compared to the last hazardous stretch.

"Unlike the previous prolonged stretch of sizzling heat, the peak of the dangerous heat for this event will last for two days," AccuWeather Senior Meteorologist Tyler Roys said. 

However, in these two days air conditioning equipment and temperature-control devices will get a real workout.

"Energy demands will be exceptionally high this upcoming week across portions of the Plains and Midwest, stressing area power grids and putting an additional pinch on residents’ checkbooks," AccuWeather Meteorologist Brandon Buckingham said. 

By midweek, the core of the most potent heat will shift fully across the Southeastern states. Conditions will ease in intensity across much of the Midwest, but temperatures will still remain slightly above what is normal for early summer through at least the end of the week.