Corn Sweats

We’ve editorialized multiple times about how fantastic firefly season is. Late June, early July, when the insects come out to tap Morse code in the grass, the days are long, the temperatures are warm, but the humidity has not ravaged our will to go outside.

The love for this window is not a blanket endorsement for summer, however.

As July wears on, the days start to get shorter, and the water in the air becomes oppressive.

Consider these disgusting graphics from the last week of July 2025:

The Mountains Are Calling HQ is experiencing relative humidity and dew points similar to the Deep South.

It’s disgusting and should be illegal. We’re in Ohio, not the bayou. Walking outside feels like walking into steaming soup.

Yet this situation is typical of mid-to-late summer.

The major culprit is the combination of weather patterns and the Gulf of Mexico. Winds stream warm, moist air from the ocean to the Midwest, allowing us to experience the hellscape of the southern summer.

If you happen to live in America’s breadbasket, things can be even worse.

Because of corn.

Outlined in the image above is the so-called corn belt.

In addition to the Gulf’s wetness, the Midwest’s agriculture has another treat, a phenomenon known as corn sweats.

Yes, corn is conspiring to make your life more humid. The scientific term for the process is evapotranspiration. Combining evaporation – water moving from the soil, for example, to the air – and transpiration – the process in which plants draw water through their roots and release it through pores called stomata – evapotranspiration is the total amount of water a crop sends into the atmosphere.

All plants evapotranspire, but corn is notorious for sweating because it is tall, which means it has a lot of stomata; further, farmers plant it densely, allowing row upon row of corn to unleash water upon the airscape.

How much could corn sweat affect the weather?

This question is insightful for two reasons, and the answer is different for both.

On one hand, it has very little to do with larger patterns. The size of the continent’s weather system is larger than a human brain can realistically comprehend. The amount of water coming from the Gulf dwarfs that coming from crops, even in aggregate. Second, water escaping from crops remains in the lower levels of the atmosphere, not high enough to become weather makers.

Still, on the other side, corn can have a shockingly high effect on local conditions. Each acre of corn can send up to 4,000 gallons of water into the air every day. A typical swimming pool contains approximately 18 to 20,000 gallons. So, every five acres sends a swimming pool aloft in 24 hours.

Ohio has about 3.25 million acres of corn. Each day, this grain evapotranspires 14 billion gallons of water in just Ohio. This amount can have a tangible impact on local humidity. And Ohio is only ninth in corn production!

Up goes the heat index.