A snow squall watch is in effect for Barrie, Collingwood, Orillia, Midland, Hillsdale, Coldwater, Washago, Orr Lake and Lagoon City, Environment Canada says.
Snow squalls are expected to develop over Lake Huron and Georgian Bay Wednesday morning.
As the wind changes Wednesday afternoon, the squalls are expected to move over the area and continue into the night.
According to Environment Canada, 10 to 15 centimetres of snow are possible by Thursday morning, with an additional two to four centimetres possible on Thursday as the squalls weaken.
The federal weather agency says visibility will likely be reduced in times of heavy and blowing snow, particularly over exposed areas.
Travel may also be hazardous due to the sudden changes in weather, Environment Canada says.