Environment Canada has issued weather advisories for the entirety of southern Ontario, stretching from Windsor all the way east to Ottawa.
The weather agency says 10 to 15 centimetres of snow is expected to blanket the region throughout Monday and into Tuesday morning.
Blowing snow is also forecast in many areas, which could reduce visibility for drivers.
Provincial police have responded to a number of traffic accidents in the GTA.
Most of northern Ontario is under an extreme cold warning, as the region is seeing temperatures drop to –40 to –50 with the wind chill.
Further east in Montreal, Environment Canada has issued a snow squall warning.