The snow is falling and it will keep going, with some 15-25 centimetres possible by the morning as a major winter storm roars across the city.

On King Street West, pedestrians pulled up their hoods and watched their footing as they navigated the snow-covered sidewalks and streets. Many piled onto streetcars or hailed cabs to get out of the snow — which came down as small, wet flakes.

Both the Toronto police and the Ontario Provincial Police responded to dozens of collisions, some involving multiple vehicles, after the snow began falling around 7 p.m.

Shortly before 10 p.m., Toronto police were forced to close the Don Mills ramp from the southbound Don Valley Parkway as cars struggled to navigate the slippery conditions.

Toronto's Pearson International Airport was forced to cancel nine flights after the snow hit. GO Transit and the Union-Pearson Express have both altered their morning schedules to cope with the major storm, which Environment Canada has been warning about since last weekend.

The heavy snowfall is accompanied by strong winds, including gusts up to 70 km/h near Lake Ontario, that are reducing visibility to nearly zero at times, Environment Canada said.

Toronto snow storm March 1

Pedestrians make their way through heavy snow on Tuesday night as a major winter storm arrives in Toronto. (Evan Mitsui/CBC)

Environment Canada is asking southern Ontario residents to consider postponing non-essential travel until conditions improve and warns that rapidly accumulating snow could make travel difficult in some locations.

City of Toronto crews began plowing major roads at 9:30 p.m. and plan to be out all night, officials said on Twitter. Sidewalk plowing, meanwhile, will begin at 10 p.m. and will also go all night.  

The city's winter operations department recommends taking public transit instead of driving.

Snowy Bike ride, toronto

The snow didn't stop this Torontonian from navigating Front Street West on his bike Tuesday morning.

Storm to end Wednesday morning

Many university and college campuses —  including York University's Keele and Glendon campuses — closed ahead of the storm.

It's unclear whether or not there will be any cancellations in the morning. 

CBC Meteorologist Jay Scotland said the storm should end by the morning hours, but it could still be problematic for morning commuters. 

"Blowing snow will likely remain an issue, especially along exposed highways, with gusty winds in the 30-50 km/h range," Scotland said. 

March a tricky month to forecast

"March tends to be a boisterous month," Dave Philips, Environment Canada's Senior Climatologist told Metro Morning's Matt Galloway. "Often what you see in March is sometimes you get winter hanging on and summer trying to get a foothold."

But Philips says don't give credence to the old saying "in like a lion, out like a lamb" when it comes to March weather.

"In 10 samples, I found it only worked three times that it either roared in and baah-ed out or vice versa, so 30 per cent is not something I would trust too much."

But he admits he does believe in the old saying, "Til April's dead, don't change a thread." 

Toronto winter storm March 1 cold

Tuesday's storm featured strong winds as well as snow, with wind chill making it feel like -17 C. (John Rieti/CBC)