A winter storm is sweeping across southern Ontario, parts of Quebec and New Brunswick, setting up for a slow commute tonight.
Toronto is now under an extreme cold weather alert and about 10 cm of snow is expected to fall on the city this afternoon.
During the evening rush hour, commuters can expect transit delays. GO buses across the GTA were experiencing delays of up to an hour early Wednesday afternoon. Most GO stations will remain open to shelter riders until the last train or bus arrives.
Greyhound bus service between Toronto and New York City has been suspended until Friday.
As the storm moves northeast across Canada from the Great Lakes area, snowfall began accumulating in Windsor and blizzard-like conditions are expected to hit Toronto.
Environment Canada has issued a special weather statement for Toronto, warning the morning snowfall could create hazardous commuting conditions.
"Most of the accumulation should be done by about 4 p.m. this afternoon, but there still will be some snow falling and there will be some blowing snow during the rush hour," said Geoff Coulson, an Environment Canada meteorologist.
The temperature in Toronto should continue to drop to –5 C, a stark contrast from yesterday's preview of spring weather.
"Many places including Toronto were experiencing sunshine and high temperatures of 10 or 11 [Tuesday] and by that same time this afternoon we could be looking at temperatures more like –7 in the GTA," Mr. Coulson said.
States south of the Great Lakes are again getting the brunt of the snowstorm. More than 13 cm has already fallen near Chicago's Midway Airport.
At Toronto Pearson Airport, at least 269 flights have been cancelled, including many mid-morning flights from Chicago and New York City.
With the start of spring less than a week away, winter isn't over yet. Coulson said Torontonians can expect unseasonably cold weather tomorrow.
"For Toronto we're forecasting a morning low on Thursday of –17, which is much much colder than our normal low for this time of year, which is –4," Mr. Coulson said.