If driving, slow down, use your headlights, and leave plenty of distance ahead of you.

DENSE FOG ADVISORY IN EFFECT UNTIL MIDNIGHT CST TONIGHT... * WHAT...Visibility one quarter to one half mile in dense fog. * WHERE...Portions of south central and southwest Illinois and central, east central, and northeast Missouri. * WHEN...Until midnight CST tonight. * IMPACTS...Low visibility could make driving conditions hazardous.