Forget the typical summer heat—it’s now the season for what some are calling “sweating corn.”
As we approach the end of July, the National Weather Service is alerting residents from Louisiana all the way to Minnesota about potentially “dangerous and prolonged heat” mixed with high humidity.
This intense humidity, especially in the Midwest and corn-growing regions, can be traced back to the multitude of crops, particularly corn, thriving in these areas.
Ellen Bacca, the chief meteorologist at Nexstar’s Wood, points out that just like us, corn and other crops can become “sweaty” when it gets hot. But here’s the thing—plants operate differently. They draw water up from their roots and release it into the air through a process known as evapotranspiration.
According to estimates from the US Geological Survey, just one acre of corn can emit between 3,000 and 4,000 gallons of water vapor daily. In fact, the National Weather Service noted that mature corn in Illinois can contribute over 35 billion gallons of water vapor in a single day—enough to fill an Olympic-sized swimming pool and then some.
Regions like Iowa, famous for their extensive cornfields, often experience some of the highest humidity levels in the nation.
On Tuesday, for instance, National Weather Service data revealed dew points soaring into the late 70s across Iowa, Illinois, Missouri, Kentucky, and Tennessee, with only Florida and parts of the Gulf having similar humidity levels at that time.
According to Brian James, chief meteorologist at Nexstar Weather Center, the impact of corn sweat is evolving. It’s moving past localized effects to much broader implications, likely exacerbated by climate change.
“More extensive corn fields are amplifying humidity levels, which has been intensified by climate change,” he stated. “A warmer atmosphere holds more moisture, so when the temperature rises significantly during summer, it leads to higher humidity levels, elevating thermal index values to over 110 degrees across a considerably wider area than what was previously observed.”
Looking ahead, NOAA’s Climate Forecast Center indicates that by the end of July, only California, parts of Nevada, Wisconsin, Michigan, and the Northeast are expected to have below-average temperatures. Most other areas, particularly along the Gulf Coast and southern plains, are likely to exceed normal temperature ranges.
However, this phenomenon of corn sweat, which contributes to the humidity we feel, will only persist for a few more months.
