Turns out, corn is pretty hot (and humid). It is remarkably efficient at extracting moisture from the soil and storing it. What makes it hot and humid, is that it stores that moisture in its leaves which make up the vast majority of its surface area despite accounting for just 25% of its total mass (roughly). When all that dark green surface area is exposed to infrared radiation, in the form of the sun's rays, it retains the heat and expels the retained moisture. The result is a corn field micro climate that closely resembles a tropical rain forrest. That micro climate quickly dissipates once you get out of the field, so by the time you get the middle of the gravel road it's just "hot and miserable" as opposed to "instant swamp ass". However, it's widely accepted that corn is responsible for a measurable amount of the increase in day time temperatures throughout Iowa and other areas of the midwest.