July 23, 2025
If you have a really calm, hot day (in Iowa), if you go near a cornfield, you definitely can feel the increased moisture just coming off the plants and whatnot.
National Weather Service meteorologist Matthew Campbell explaining how humidity from “corn sweat” will intensify this week’s heat wave spreading across the Midwest and the South. Like all vegetation, corn releases moisture in a process called evapotranspiration, which boosts dew points in the atmosphere and makes it feel more humid.
Why It Matters: This week, some regions in the United States under a heat warning will see even higher “feels like” temperatures due to a heat dome combined with additional humidity from “corn sweat.”
Did you know? In Ohio, between 10 and 14 billion gallons of water are added to the atmosphere each day due to “corn sweat” – enough to fill up to 21,000 Olympic swimming pools.
Learn More:
- ‘Corn Sweat’ Is Making This Heat Wave Even Worse (Scientific American)
- What is ‘corn sweat,’ and does it affect Midwest humidity? (The Columbus Dispatch)
- A heat dome and “corn sweat” are driving this week’s dangerous heat wave (Axios)
by Stephanie Wagner, based in Florida
