Environment Canada is advising of difficult travel conditions due to snow covered roads.
The national weather agency issued an advisory for Sarnia-Lambton just before 4:30 p.m. Friday.
It said rain has changed to snow in many areas of the region and will end later Friday evening.
The alert said roads are quickly becoming snow covered and up to five centimetres of snow accumulation is possible.
Temperatures will continue to drop well below the freezing mark early this evening.
Motorists should expect hazardous winter driving conditions and adjust travel plans accordingly.
Surfaces such as highways, roads, walkways and parking lots may become icy and slippery. If visibility is reduced while driving, slow down, watch for tail lights ahead and be prepared to stop.