What ‘Corn Sweat’ Is and Why Everyone’s Talking About It

iStockphoto / Sarah Uphoff designs

A sweltering heat wave is currently raging across the Midwest, with approximately 61 million Americans currently under extreme heat warnings and advisories as temperatures in Illinois rival Florida and many are experiencing “real” wind chill temperatures of over 113 degrees. As all of this is unfolding, millions of Americans are suddenly learning the term “Corn Sweat,” as it is believed that Corn Sweat is making the heat wave worse, leading to record temperatures for millions.

What is corn sweat? A colloquial term for evapotranspiration

The definition of evapotranspiration (ET) in ‘A Dictionary of Earth Sciences’ is: “water lost from the surface of soil or open water as vapor (evaporation) and from the surface of plants as water vapor (transpiration).” Due to the current weather in the Midwest, evapotranspiration (ET) is being called “Corn Sweat,” and for good reason.

A single acre of corn can release up to 3,000 gallons of water into the atmosphere per day. The state of Iowa boasts 12.9 million acres of corn. Illinois boasts 10.9 million acres of corn.

Of course, *not all* acres are releasing 3,000 gallons of water into the atmosphere every day, but with the current heat dome slamming the Midwest, let’s assume for the sake of this thought experiment that they all released that today. That would be approximately 71,400,000,000 gallons of water released today via “Corn Sweat” across the Midwest due to these record breaking temperatures.

In this thought experiment, that would equate to approximately 108,181 Olympic-sized swimming pools full of corn sweat being released into the atmosphere, raising the relative humidity through the roof from Kansas City to Washington, DC. In fact, many media outlets are outright claiming that evapotranspiration (ET) or “corn sweat” is a major contributor to this heat wave sweeping across the Midwest.

Who says what?!

Scientific American says: “A heat wave is sending temperatures soaring across the Midwest, and ‘corn sweat’ is sending humidity skyrocketing.” NBC 5 Chicago writes: “All of northern Illinois is under an extreme heat warning on Tuesday, but a phenomenon known as “corn sweat” will make conditions even more challenging.”

WTOL meteorologist Chris Vickers says, “One acre of mature corn can release 3,000 gallons per day! This is contributing to the extreme oppressiveness we are currently experiencing,” and shared this graphic of how it all works:

Here’s some more info on how this Corn Sweat thing works. photo.twitter.com/BYQtBL17l6

— Chris Vickers (@ChrisWTOL) August 26, 2024

Other meteorologists in the Midwest are busy compiling clips explaining this regional weather phenomenon:

Is Corn Sweat the Direct Cause of the Midwest Heat Wave? Not Necessarily

There are currently two major factors contributing to the record temperatures in the Midwest: moist air rising from the Gulf of Mexico, bringing a heat wave from Texas… and corn sweat. It’s worth noting that this isn’t just caused by corn. Other Midwestern crops, like soybeans, also produce evapotranspiration (ET).

So this is a two-way front: very hot, very humid air that will batter the Midwest for the next few days.

I spoke to at least one person on the BroBible team who has lived in Illinois/Iowa his entire life and he claims he has never heard the term “Corn Sweat” before until now. There is no reason to believe him. I have heard a similar report from other friends who live in Illinois who I reached out to for comment.

While this is a nickname for a very real phenomenon, evapotranspiration (ET), it seems the mainstream media is looking for something to talk about as the Atlantic tropics are unusually quiet for this time of year…