Significant snowfall over northern Ontario is expected to move west to east over the region starting Wednesday morning.
Environment Canada has issued snowfall and winter weather warnings for much of the area.
The agency says up to 20 centimetres of snow is expected in some locations.
Drivers in the Thunder Bay and Kenora areas are warned of potentially hazardous road conditions, with heavy snow and strong winds.
Snow is also forecast in Sudbury and North Bay before turning to rain by evening.
Residents in the eastern part of the region are being warned of the potential for another heavy snowfall on Christmas morning.