A phenomenon called "corn sweat" could exacerbate the impacts of the extreme heat blanketing a large portion of the U.S., according to experts.

The millions of acres of corn grown in states like Ohio, Illinois and Iowa perspire just like any other plant. A single acre sweats 3,000 to 4,000 gallons of water every day.

Corn sweat, a Midwestern phenomenon, could increase humidity levels in already-sweltering states—from Ohio to Illinois—through Thursday.