Dense fog this afternoon could reduce visibility to a quarter mile, so drivers should should use headlights, slow down and leave extra distance between vehicles, according to the National Weather Service.
A dense fog advisory has been issued for Lake, Porter, Newton and Jasper counties until 6 p.m. Monday, and in LaPorte County until midnight.
The heaviest fog has been observed south of Interstate 80, though conditions could improve as more rain moves in this afternoon, forecasters said.
Heavy fog also is likely overnight into Tuesday morning, the weather service said.
The advisories followed warnings earlier Monday of possible rain or freezing rain, especially in areas north of I-80. A chance of freezing rain in LaPorte County is expected to continue into Monday afternoon.
With the rain comes a limited risk of isolated thunderstorms, but severe weather is not expected, the weather service said.