National Weather Service United States Department of Commerce
...UPDATED INFORMATION ABOUT HAZY/SMOKY CONDITIONS...

Prairie grass burning was NOT being done around Lake Springfield
today, but occurred yesterday. However, smoke from numerous spots
doing burning earlier in various parts of central Illinois,
combined with dirt and dust from a dry ground and harvesting has
caused the hazy visibility and smoky smell. An increasing
southwest wind gusting to 25-30 mph will allow the hazy visibility
and smoke to improve early this afternoon.

In addition, smoke from the western wildfires at higher levels in
the atmosphere, about 5 to 6 miles aloft, are giving the sky a
hazy and milky appearance across all of northern and central
Illinois.