Some Scientists Blame Recent High Humidity in Kentucky on ‘Corn Sweat’

By Zoe Lewis

Even in the dying days of summer, many Kentuckians are facing high humidity and heat indexes. Some scientists say corn crops could be partially to blame.

An environmental phenomenon known as “corn sweat” has gained traction on the internet. It’s the silly name for the biological process known as evapotranspiration, which occurs when corn plants pull water from the soil to cool down and release it back into the air as vapor. This process, when carried out by acres of corn crops, has been shown to increase a region’s humidity.

A 2020 study from the Harvard-Smithsonian Center for Astrophysics analyzed data from past heat waves and found that cropland, including corn, can increase moisture levels in the air by up to 40%.

Shane Hollinde, the Outreach Manager for the Kentucky Climate Center, said the humidity comes from neighboring states, like Illinois, who start their corn season later in the year compared to Kentucky.

“You’re seeing more corn sweat in that part of the world because the corn there is still greener. It’s in mature form, whereas the corn here in Kentucky has already gone through its cycle of growth and maturity,” Hollinde said.

The state of Illinois has about 12 million acres of corn crops, Hollinde said, and each acre is capable of releasing around 4,000 gallons of water a day. According to Hollinde, the process could put as much as 48 billion gallons of water – the equivalent of a little more than 72,000 Olympic pools – into the air over Illinois each day.