Environment Canada has issued a wind warning for Toronto and much of southern Ontario as winds are expected to gust up to 100 km/h on Tuesday night and continue into Wednesday.
Temperatures are expected to reach an above-seasonal high of 5 C on Tuesday, but then plummet to a low of -9 C by Wednesday morning.
The temperature change is the result of a cold front moving in from northern Ontario, which will draw a strong blast of cold Arctic air behind it.
"The cold front from this system is expected to sweep through southern Ontario tonight, reaching Windsor by midnight and Toronto by 6 a.m. or 7 a.m. Wednesday morning," read a statement on Environment Canada's website on Tuesday.
The weather service says the high winds could bring down power lines and trees. Some regions could see ice pellets and blowing snow on Wednesday, Environment Canada says.
A wind chill warning has been issued for northwestern Ontario, as the mercury is expected to drop to -40 C on Tuesday night. Some areas will see 10 to 20 centimetres of snow, with another five to 10 centimetres on Wednesday.
Environment Canada has issued a winter storm watch for northern Ontario, warning of heavy snowfall and blizzard-like conditions on Tuesday night and Wednesday.