Special Weather Statement issued August 20 at 3:39PM CDT by NWS
Effective: noon on Sunday, Aug. 20, 2017
Expires: 4 a.m. on Monday, Aug. 21, 2017

...Afternoon Heat Index Values 100 to 105 Degrees Monday...
The heat and humidity will continue across the region Monday.
Although the eclipse itself will provide some temporary relief
from the heat, heat index values will still reach at least the
upper 90s throughout the region after it ends. The worst
conditions will be over southeast Missouri, southern Illinois and
the Purchase Area of Kentucky where readings will range from 100
to 105 degrees. Isolated thunderstorms will be possible over
portions of southeast Missouri and southern Illinois in the
afternoon, so a few locations may receive some more significant
relief from the heat.
If you are planning to view the solar eclipse or participate in
other outdoor activities, then please bring along plenty of water
to keep hydrated. If you have any opportunity to do so, take
breaks in the shade or in an air conditioned building.
A cold front will bring storms through the region on Tuesday and
cooler temperatures for the remainder of the week.

See more at NOAA