Corn sweats? Yep, and impacts our summer weather doing it


ST. LOUIS – In the summer, we love to eat corn, fresh and sweet. In the fall, we love to get lost in it. Corn maze season is upon us.  

“It’s kind of a tradition. Every generation…we’ve gone through several generations now that keep coming back.  So yeah, I think everybody enjoys it,” Dave Thies said.  

His Thies Farm is well-known for its corn maze and other Fall fun at its Hanley Road location. 

“We don’t plant our corn until mid-July so that we have a green cornfield come July instead of a dried one. Makes it a little safer for fire problems and I think it is just nicer.” 

But growing corn can be a steamy experience. During our hottest stretches, did you know corn can make conditions even more uncomfortable? 

“Yeah, cornfields are a little bit rough,” Thies said.

Plants release carbon dioxide and excess water vapor from their leaves when they “breathe” or transpire. Water also evaporates from the soil. That moisture is carried by the wind into the surrounding areas. This evapotranspiration, often called “Corn Sweat,” can add an estimated three to four thousand gallons of water vapor to the atmosphere per acre per day during the height of corn season, according to the U.S. Geological Survey.  

“The respiration rate is so high that it puts so much humidity into the air. And I guess, also collects that radiation,” says Thies. “And if you are in a cornfield, there’s absolutely no airflow whatsoever because it is so tall.” 

That added moisture raises humidity, so our sweat doesn’t cool us down as efficiently. When the air is more humid, temperatures don’t drop as much overnight, meaning even the earliest starts are still warm. And all that extra moisture can help fuel thunderstorm growth.  

“I just talked to a big corn grower. He said he was there standing by the field and it was reading 97 degrees at the cornfield as compared to mid-80s elsewhere,” Thies said. 

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