Dense fog and below-zero temperatures have made parts of the province dangerous for travel.
A fog advisory was issued for Grey, Bruce, Huron, Perth, London-Middlesex, and Sarnia-Lambton Counties early Sunday morning.
Environment Canada said that areas of dense fog are expected to dissipate by the afternoon.
"Visibility may be significantly and suddenly reduced to near zero," the weather agency warned. Drivers are advised to slow down, watch for tail lights ahead, and be prepared to stop.
Below freezing temperatures combined with the fog have also caused concern, as untreated roads and walkways could become slippery and icy.