Environment Canada issued a weather alert for Tuesday night, warning of freezing rain and snow with potential for the first blast of winter weather this fall.
Snow and freezing rain are possible from Belleville to Prescott and Russell to Bon Echo Park, including the city of Ottawa.
Ten centimetres of snow is possible in some areas by Wednesday morning.
Environment Canada said a low pressure system that developed in the United States Tuesday afternoon is expected to track northeast across Ohio and into Pennsylvania by Wednesday morning.
Cold air in Eastern Ontario could lead to precipitation falling as snow or a mix of snow and rain with a chance of freezing rain, the alert said.