Sweltering summer heat wave to take aim at Midwest into Sunday

By Alex Sosnowski, AccuWeather senior meteorologist

June 30, 2018, 5:32:46 AM EDT

A heat wave will reach its peak in the Midwest this weekend, but a turn to more refreshing weather is not expected to follow for the Fourth of July.

Across the Northern states, a heat wave is described as three or more days in a row with high temperatures at or above 90 F.

While the northeastern United States is bracing for some of the longest hot weather of the year so far into next week, the wave of heat will hit, peak and become dangerous sooner over the Midwest.

The heat from Friday is expected to hold on Saturday with widespread highs in the 90s expected from Wichita, Kansas, to Chicago, Green Bay, Wisconsin, and Detroit.

The heat will challenge record highs in some communities.

On Thursday afternoon, the temperature in Denver reached 105. This tied the city's all-time record high temperature, last reached in 2012.

While the evaporation of moisture from the ground due to the relentless downpours of late will limit maximum temperatures somewhat, the moisture in the air will result in oppressive humidity levels along with the heat.

AccuWeather RealFeel® Temperatures will surge to between 95 and 110 over a broad area for several hours during the midday and afternoon.

Homeowners without air conditioning may want to set up an area in a cool basement to spend time out of the heat.

The heat and humidity will bring an elevated risk of heat exhaustion and heatstroke.

In urban areas of the major cities, such as Chicago, St. Louis, Detroit and Cincinnati, cooling stations will be needed. The vast expanse of concrete and pavement will give off heat at night and make sleeping difficult without air conditioning.

People who must partake in manual labor or feel the urge to exercise should try to do so when temperatures are lowest, such as the early-morning, evening and overnight hours.

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People are urged to drink plenty of liquids and limit their intake of alcohol in weather patterns such as these. Alcohol can accelerate dehydration.

Be sure to check on the elderly, young children and pets on a regular basis. If your pet cannot be brought indoors to a cool place, make sure they have a shady area and plenty of fresh water.

Motorists are encouraged to reduce their speed on the highway and keep tires properly inflated to lower the risk of a blowout during extreme heat.

The heat wave is projected to break down from northwest to southeast as a swath of thunderstorms advances from the northern Plains into early next week. Some of the thunderstorms may turn severe with the threat focusing on the I-35 corridor on Saturday afternoon.

The heat wave will hold for one more day from St. Louis to Chicago and Detroit on Sunday before thunderstorms trim temperatures slightly by Monday.

While the peak of the heat will have passed, comfortable weather is not in the offing for the Fourth of July.

Highs within a couple degrees of 90 are expected on Independence Day with humidity keeping AccuWeather RealFeel® Temperatures higher. Widely separated thunderstorms may dot the region on the holiday, mainly during the afternoon and evening hours.

"In the heart of the Midwest, temperatures are likely to remain well above average through much of the first half of July," according to AccuWeather Long-Range Meteorologist Max Vido.

"The dog days of summer are setting in, perhaps a little ahead of schedule," Vido said.

The dog days of summer are typically from July 3 to Aug. 11 in the U.S., according to the Old Farmer's Almanac.