Environment Canada has issued rainfall and freezing rain warnings across eastern Ontario and western Quebec.
Rainfall warnings were put in place late Friday afternoon in Ottawa-Gatineau, as well as other Ontario communities like Kingston, Smiths Falls, Cornwall and Brockville.
Most areas will receive between 20 to 30 millimetres of rainfall by Saturday night, with that precipitation then changing to freezing rain, the weather agency said.
That freezing rain may last for several hours before turning into ice pellets mixed with snow Sunday.
"Significant ice accretion of 10 to 20 mm is possible Saturday night from the freezing rain. Freezing rain warnings will likely be issued as this event draws closer," Environment Canada said.
In the Kingston, Belleville and Napanee areas, precipitation is expected to be even heavier: as much as 40 to 60 millimetres of rain is expected to fall by Saturday evening.
As the ground is frozen and has a "reduced ability" to absorb all the rain, flooding could be possible, Environment Canada warns.
Western Quebec, Pembroke under freezing rain warnings
A freezing rain warning, meanwhile, is in effect for much of western Quebec, including Maniwaki, Low, Wakefield, Gracefield, the Lièvre River area, the Labelle Reserve area, Papineauville and the Chénéville area.
The warnings also cover certain parts of eastern Ontario, particularly the Pembroke and Bancroft areas.
"Freezing rain is expected or occurring," Environment Canada said just before 4 p.m. Friday.
Between 10 and 20 millimetres of freezing rain is expected in the region.
"The rain is expected to turn over to freezing rain and ice pellets by Saturday evening then to snow later Saturday night," Environment Canada said.
High winds could also arrive Sunday across eastern Ontario and western Quebec, the agency said, leading to potential power outages.