And yes, it can absolutely affect you -- here's what to know.
While the unofficial summer season is now over, heat continues to blanket several parts of the U.S. Last week, the Midwest experienced record-setting high temperatures that were allegedly made even worse by a surprising culprit: corn.
A natural phenomenon known as "corn sweat" can make hot temperatures even more intense, creating uncomfortable conditions for people in the vicinity of this crop. While corn sweat isn't an official scientific term, it's still a process that scientists understand and recognize. Here's the deal with corn sweat, plus how to stay safe if you happen to get caught in it.
Corn sweat is a term that's used to describe evapotranspiration (ET), which is a natural process where plants -- including corn -- move water to the surface. That water then evaporates into the surrounding atmosphere, creating uncomfortably muggy conditions. While the corn doesn't actually sweat in the conventional sense, it does give off moisture. Research conducted by the USDA's Agricultural Research Service suggests that corn can pump out thousands of gallons of water per acre into the atmosphere over just a few days. One study from 2020 also attempted to quantify just how intense corn sweat can be and found that sweaty corn can increase moisture in the air by up to 40%.
"When you have a heat ridge centered across the corn belt region, the corn can actually emit increased levels of humidity and dew point temperatures," says Michael Musher, a meteorologist and spokesperson for the National Weather Service. But moisture also goes into the air when water in the soil evaporates, creating an especially intense environment for people around it.
Related: 28 Tasty Corn Recipes, from Succotash to Corn on the Cob
There are more than 127 million acres of agricultural land in the Midwest and 75% of that is made up of corn and soybean crops, according to the USDA. But it's important to note that this applies to a wide range of crops and isn't just specific to corn -- it's just mostly linked to the crop.
Even meteorologists in corn-heavy areas talk about corn sweat. Chris Vickers, a meteorologist in Toledo, Ohio, shared a hilarious graphic in late August featuring corn over areas that were experiencing particularly high humidity and heat.
The big concern with corn sweat is the impact on the local heat index, i.e. what the temperature feels like when you factor in humidity, per Musher. Corn sweat can "make the apparent temperature or heat index and heat risk oppressive and quite dangerous," he says.
That doesn't mean you're doomed if you happen to live near a field of corn, but it's important to pay attention to the heat index, according to Lewis Nelson, M.D., chair of emergency medicine at Rutgers New Jersey Medical School. High heat indexes can lead to heat illness like heat exhaustion, which can cause uncomfortable symptoms like nausea and vomiting, muscle cramps, heavy sweating, dizziness, weakness, and headache, he points out.
"If you pay attention to it and you feel it coming on, you can mitigate it through cooling and hydration to quickly recover from it," Nelson says. "But if you don't pay attention to it, it can progress to heat stroke. That is truly a medical emergency."
The heat wave in the Midwest seems to have cooled slightly but, if you happen to live near fields of corn, corn sweat is a phenomenon to have on your radar for the future.