Believe it or not, parts of the American Midwest see some of the hottest temperatures in the world during summer months. While the actual temperature may not be all that impressive — 100°F is commonly reached all over the world — the Midwest humidity can make it feel much, much worse.

We often talk about the “dewpoint” when the humidity really cranks up.

A dewpoint is a measure of moisture. The more moisture there is in the atmosphere, the harder your body has to work in order to stay cool. Your body really sweats once the dewpoint starts to get above 60°F. Once the dewpoint gets above 70°F, you might need the air conditioner in order to stay cool. Dewpoints in the 60’s and low-70’s are common throughout the world; when it gets above 80°F, then a different can of worms is opened.

Dewpoints near and above 80°F are not too often reached around the world, even in the tropics. Such dewpoints can be readily touched when you have a lot of moisture evaporating–turning into water vapor–into the atmosphere. Parts of the Midwest are havens for this steam-bath potential.

By June and July, not only are rivers giving off lots of water vapor, but so are new plants, too: young plants, like the soybeans, corn and alfalfa, give off tremendous amounts of water vapor (sometimes more so than many of the established flora and fauna of the tropical rainforests). If you add high soil moisture content (from heavy spring rains) to the mix, then you have all the ingredients for near 80°F+ dewpoints. This is often the case right here in Northeast Kansas.

Northeast Kansas, Northern Missouri, Eastern Nebraska, Southern Minnesota, all of Iowa, Southwest Wisconsin and much of Illinois, all share in the potential for near 80°F+ dewpoints because of the combo of rivers, lakes and lots and lots of perspiring crops. It’s really the crops that do the trick in pushing that dewpoint towards 80°F. June and July are usually the worst of this combo. By the time we hit August, many crops mature. Maturing crops do not give off quite as much water to the atmosphere. So, by August, we usually see those dewpoints cap off in the low-to-mid 70’s, at best.

What does all of this mean? It means you do not have to live in the tropical rainforest to “feel” the highest humidity you can get. Factor in a hot Northeast Kansas sun, and actual temperatures near 100°F, you have a potentially lethal heat index pushing 110-120°F+; if those actual temperatures are combined with dewpoints pushing 80°F.

All of the ingredients are in place this June and July for near 80°F dewpoints to continue to be realized in and close Northeast Kansas. This means with each heat wave for the next few weeks, we have the potential for seeing heat index values topping 110°F. We will likely have to wait now until August before this dangerous potential wanes. Get ready for a hot, no doubt humid, summer in Northeast Kansas.