The "sweat" on the corn refers to transpiration, where water from the leaves moves up into the atmosphere through humidity.

DECATUR, Ill. (WAND) -- Just one step outside could leave you in a puddle of your own sweat. The corn stretching as far as you can see is not helping.
 
The corn is sweating with you this week.
 
"It's been called corn sweat because a lot of the humidity gets blamed on corn," said University of Illinois State Climatologist Trent Ford. "It is just a little bit of water, but when you multiply that by the leaf area, you think about this time of year in Central Illinois, and when you add all of that up, it can actually make for quite a lot of water that is being transferred from the ground to the atmosphere in the form of humidity."
 
The "sweat" on the corn refers to transpiration, where water from the leaves moves up into the atmosphere through humidity. One plant produces a little bit of water, but an entire acre produces much more.
 
Corn "sweating" is actually a good indicator for the crop.
 
"The fact that we are getting corn sweat and the fact that it is transpiring suggests that we have, at least in most places, a pretty healthy crop out there in abundant soil moisture for that crop to pull in that water from," Ford said. 
 
Still, corn sweat is a small contributor to humidity.
 
"It is significant, it's not negligible, but it is relatively small," Ford explained. "The vast majority of the humidity that we're experiencing is most often coming from the Gulf of Mexico."
 
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