Environment Canada has issued a winter storm watch for Ottawa and eastern Ontario with the risk of "significant" freezing rain and snow.
According to the weather agency, areas west of Ottawa could see snowfall amounts of 15 to 30 centimetres while areas to the east of the city will see mostly freezing rain.
The storm is expected to begin with freezing rain Saturday evening, then change to ice pellets before turning into snow by Saturday night. The snow will turn into flurries around noon Sunday.
Environment Canada did not say how much snow is expected in Ottawa as it depends when the rain turns to snow.
People are asked to avoid travel if possible.