Hot, muggy weather in southwest Illinois ties heat record. ‘Corn sweat’ isn’t helping

The St. Louis metro area tied a heat record from 1881 Tuesday, and the region, including St. Clair County, is under a heat advisory through Thursday evening.

As many Midwest residents have experienced, air temperature is just one contributing factor to how hot it feels outside. Humidity can bring the heat index up significantly, and “corn sweat” only adds to the moisture in the air.

“Corn releases moisture through evapotranspiration and that is one of the reasons why we get fairly humid here in the Midwest, because there is a lot of corn around,” Jon Carney, National Weather Service St. Louis office meteorologist, said in a Tuesday interview with the BND.

Soybeans can also raise the humidity level, and Carney said standing next to either crop in July or August can feel significantly warmer than other Illinois areas.

Safety tips for extreme heat

The forecast for Wednesday is cooler than Tuesday, but NWS meteorologists still expect heat index values as high as 100 in Belleville . Tuesday’s high was 102 degrees, which hadn’t been seen on an Aug. 27 since 1881.

It’s best to stay inside when possible in extreme heat, Carney said, but if you need to work outside be sure to drink lots of water, take breaks indoors and stay in the shade as much as you can.

“If you start to feel ill, dizzy, sick to your stomach, sweating profusely but not cooling off, those are all signs of heat stress. You should really get out of the heat at that point,” Carney said.

It can also help to wear loose-fitting, light-colored and light-weight clothing.

A chance of showers and thunderstorms Friday and Saturday should bring some relief from hot temperatures. NWS forecasts Belleville will see highs below 90 degrees Saturday and Sunday, and Labor Day and Tuesday will likely have high temperatures below 80 degrees, according to the forecast.

Fall officially begins Sept. 22, and the NWS reports the metro-east may see above-normal temperatures, while the Farmers’ Alamnac predicts a cooler season .

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