Meteorologists and atmospheric researchers say the Midwest's first dangerous bout of heat and humidity this summer is partly to blame on moisture piped out of the ground and into the atmosphere by the increasing acreage of corn crops reaching their peak.
That muggy air gets blown around the country, even enveloping urban areas, like Chicago and Minneapolis.
The phenomenon spawned playful banter on social media this week about the menace of "corn sweat."
The technical term is evapotranspiration. When corn crops mature, they act like billions of straws drawing up soil moisture.
It beads up on leafy canopies and is carried off by warmer air.