Freezing fog created some slippery roads Friday morning , but temperatures were expected to rise above freezing by noon, lifting the fog and glaze.
The warmer temperatures will be a welcomed relief for many, but could bring flooding problems with them.
The warm up marks the first time the region has seen temperatures above freezing since Dec. 29.
Lake, Porter, Cook and Will counties are under a freezing fog advisory until noon. The National Weather Service said visibility could be reduced to less than a quarter of a mile.
When freezing fog occurs, icy patches can develop on sidewalks, untreated roads, bridges and overpasses.
Indiana State Police said the Indiana Toll Road was particularly slick Friday morning.
Police and forecasters were urging motorists to reduce speeds and increase following distance.
When the fog lifts, the region is expected to see rain start to fall, with up to an inch possible by midnight. The above freezing temperatures coupled with the rain could cause flooding as the snow begins to melt.
Chicago's south suburbs and Northwest Indiana have anywhere from 6 to 12 inches of snowpack, which has a water equivalent of 1 to 2 inches. Snowpack totals are different from snowfall accumulation totals and mark the amount of snow that has fallen and massed together over time.
The frozen ground, ice-covered rivers, melting snow and additional rain could cause increased runoff and flooding.
The National Weather Service urged residents in low-lying, flood-prone areas to closely monitor the forecast throughout the next several days.
High temperatures are expected to be above freezing through Tuesday.