Is ‘corn sweat’ causing Kansas City’s very humid summer? Here’s what experts say
It sure has been a muggy summer in Kansas City — one of the worst in the past 50 years, according to weather data.
This July saw 13 consecutive days with dew point values — a measurement of how much moisture is in the air — at or above 75 degrees, tying the previous longest streak set in August 1995, Iowa Environmental Mesonet data show.
Average daily dew point values for Kansas City in July were also the fourth highest in the past half-century.
Recently, national and regional media have blamed a phenomenon known as “corn sweat” for the steamy weather, not just in the metro but across the Midwest.
The Star reached out to experts to find out how much corn sweat really is to blame.
What is corn sweat?
Corn sweat has become the popular phrase for what is scientifically known as evapotranspiration, the combination of moisture evaporating from the ground and water released from the leaves of plants like corn and soybeans, said Chris Bowman, a meteorologist with the National Weather Service in Kansas City.
Corn sweat is real and can affect humidity. But can that effect be seen in the Kansas City area?
“We can, perhaps not in the urban area of Kansas City,” Bowman said. “But when you get out to the rural areas where the agriculture occurs, it is a thing.”
While corn sweat has the strongest, most noticeable effect on humidity near large corn fields, it can spread beyond the farmland.
Corn sweat can have some impact on urban areas, said Tom Di Liberto, media director at the climate science nonprofit Climate Central. It creates a moisture source that otherwise wouldn’t be there, allowing dew points to remain higher than they would otherwise be.
“It’s something you don’t think about when you look at like rows and rows of corn,” Di Liberto said.
That moisture evaporating into the atmosphere can lead to an increase in humidity and even more rain showers, depending on wind patterns, Di Liberto said.
“That can easily move over urban areas, and you can have that sort of influence depending on where the wind is blowing to,” Di Liberto said.
‘Never-ending conveyor belt of moisture’
Much of the central and eastern United States was locked in consistently moist air during July, Di Liberto said.
“July is normally the most humid month of the year to begin with, but even with that said, this month has been relentless for a lot of places,” Di Liberto said.
Besides corn sweat, two main factors contributed most heavily to this unusually humid summer. One is the long-term trend of warming temperatures due to climate change, which means the atmosphere can hold more moisture, Di Liberto said.
The second factor is that the Bermuda High, a high-pressure system usually off Bermuda, shifted more to the west than usual, pushing sustained moisture into the region. The Bermuda High was also over water that is warmer than average.
“What that's doing is allowing for a pretty consistent stream of moisture to get pushed into the central and eastern United States — this kind of like never-ending conveyor belt of moisture,” Di Liberto said.
This story was originally published August 7, 2025 at 6:00 AM.
