Special Weather Statement issued June 15 at 10:56AM CDT by NWS
Effective: noon on Friday, June 15, 2018
Expires: 4 p.m. on Friday, June 15, 2018

...Very hot and humid through the weekend...
Afternoon heat index values will top out from 100 to 105 west of
a Mount Vernon Illinois to Cadiz Kentucky line today. At 1045 AM
CDT, the heat index was already approaching 100 degrees in some of
these locations.
Over the weekend, the heat will build east, with afternoon heat
index values 100 to 105 degrees across all of southeast Missouri,
southern Illinois, southwest Indiana and west Kentucky. Some
locations may see readings exceed 105 degrees this weekend. A Heat
Advisory will likely be required.
Those with outdoor activities Friday, and especially this weekend,
should plan to wear lightweight and light colored clothing if
possible. Take frequent breaks from the heat in the shade or
preferably an air conditioned location. Remember to bring along
and drink plenty of non-alcoholic beverages. Make sure pets have
adequate shade and fresh water.

See more at NOAA