Dangerous driving conditions have developed with visibility dropping to near zero in many spots west and north of Chicago early this Thursday morning. A Dense Fog Advisory is in effect for Winnebago, Boone and McHenry Counties with patches of near zero visibility also observed in Ogle, Lee, DeKalb, Kane, LaSalle, Grundy, Kendall, Du Page and Will Counties, as well as across southern Wisconsin. This includes segments of I-90, I-80, I-39 and I-88.
Temperatures have dropped to the upper 40s and lower 50s – matching the dew point, creating near 100 percent relative humidity and the dense fog formation. So if you’re out driving this morning, be aware of rapidly changing visibility to near zero in some locations. As temperatures rise, visibility will gradually improve across the area by mid-morning.