08/31/2026
Some really interesting information about the heat, corn sweat, and humidity.
This week’s heat looks more like summers from 50+ years ago.
In the peak of summer, corn and soybeans pump a lot of water into the air in a process known as evapotranspiration, better known as "corn sweat."
That moisture keeps the actual temperature from climbing as high, but it makes it feel hotter. That’s why 100° on the thermometer has become uncommon in the last few decades, while heat-index readings over 120° are becoming more common. Higher dew points = higher heat indices.
Right now, the crops are drying down and turning yellow and brown before harvest. They add less moisture to the air. Drier air is easier to heat, so the thermometer can climb higher. A few spots could hit 100° by Wednesday or Thursday thanks to less moisture (though it will feel humid).
Corn yields have roughly doubled in the last 50 years, averaging about 105 bushels per acre then to over 215 now. Growing more efficient corn means moving more water during the summer season. More water v***r = less likely to hit 100°. But, the chance to hit 100° is more likely either during severe drought or as we approach the harvest season - which is where we are now.
I don't think we hit 100° along I-57, but perhaps closer to the Illinois River and along I-55, we could get really close, if not hit it Wednesday/Thursday.
Last time 100° was reported:
Urbana: 2012
Willard Airport: 2022
Springfield: 2012
Decatur: 2012
Mattoon-Charleston: 2012
Danville: 2012
2012 was a severe drought year, for those who remember. Willard sometimes runs a little hotter than everyone else, so they got there in 2022.
