The Midwest is bracing for a brutal heat wave this week, and millions of acres of corn crops are about to make it feel even worse. As temperatures soar across the region, a natural process called evapotranspiration — commonly known as corn sweat — will pump billions of gallons of water vapor into the air, driving humidity levels through the roof.
How corn makes hot days feel hotter
Despite its nickname, corn sweat has nothing to do with actual perspiration. The process occurs when plants release water vapor through their leaves into the atmosphere. During peak growing season, this natural phenomenon becomes particularly intense across the Plains and Midwest, where corn and soybean fields stretch for millions of acres.
The science behind it is straightforward but the impact is staggering. Water evaporating from corn plants enters the atmosphere and combines with existing moisture, significantly increasing humidity levels. On already hot summer days, this added moisture makes the air feel thick and oppressive, turning uncomfortable heat into something far more punishing.
The numbers are mind-boggling
The sheer volume of water that corn releases into the air during summer months is difficult to comprehend. According to the U.S. Geological Survey, a single acre of corn releases between 3,000 and 4,000 gallons of water into the atmosphere every day during growing season.
When you multiply that by the millions of acres under cultivation across the Midwest, the numbers become astronomical. In Iowa alone, corn fields pump out an estimated 49 to 56 billion gallons of water into the atmosphere daily, according to the National Weather Service. That massive amount of moisture can raise dew points by 5 to 10 degrees on hot summer days…