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

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

An acre of corn can release 3,000 to 4,000 gallons of water into the atmosphere a day, increasing humidity levels.