The entire Mississippi River valley is miserable with humidity this time of year. On top of that there has been high levels of rain fall this spring and summer which has added to it.
There has been a “swath” of repeated hefty rains through Central and Southern Illinois , catching much of Missouri and also the lower Ohio River Valley, the last few weeks, after a very wet May and June. Some years the spigot turns off in early July, but, not this year. The corn, except for some places where it either drowned or got blown down, looks fantastic. So do the weeds, but all do add to the humidity: Our local NWS office (Paducah) even admitted the models were underestimating the effect of the evapotranspiration juicing up the area lower atmosphere, priming added thundershowers, etc. It’s a classic case of “It’s not the heat, it’s the humidity.” And there’s almost no breeze except for a few of those t-showers popping up.
The Paducah NWS radar image is showing fewer of those t-showers today, as despite the sauna-like air mass, there isn’t much to trigger them, but where present, they are not moving much. I wouldn’t be surprised to see an isolated flash flood warning or two.