Toronto Transit Commission streetcars wait for tracks to be cleared on Broadview Avenue in east Toronto on Wednesday morning. (Timothy Neesam/CBC)

A major snowstorm that is moving out of southern Ontario wasn’t as intense as predicted, but packed enough of a punch to cause widespread school closures, commuting headaches and travel disruptions.

Environment Canada on Wednesday morning called off a storm warning for an area stretching from Windsor to Toronto as the system moves eastward.

Some areas could have snowfall accumulations of between 15 and 20 centimetres by the time the storm moves out of the province later Wednesday. The agency had predicted that the storm, which originated in Texas and wreaked havoc on the U.S. Midwest Tuesday, would dump up to 30 centimetres of snow in some areas.

The storm hit harder in southern Quebec, where drivers had to deal with blowing snow and low visibility. There were also multiple flight delays and cancellations in Montreal as up to 25 centimetres fell.

"The system's moving a little bit faster, a little more drier air coming into it," said Environment Canada's Geoff Coulson.

"So we're likely more talking about general accumulation in and around the 15-centimetre mark in most locations, but larger amounts still anticipated on the western parts of Lake Ontario."

CBC meteorologist Johanna Wagstaffe said the type of snow that fell had something to do with the lower levels of accumulation.

"We didn't get that light fluffy snow that would have piled up. Instead, [we got] that hard crystallized snow that's making the roads slippery," she said.

Hamilton, London and Sarnia faced blizzard conditions for several hours early Wednesday, while Windsor was being pounded by ice pellets just before the morning commute. Hamilton and Burlington were "by far" among the hardest hit areas, with about 20 to 25 centimetres of snowfall, Wagstaffe said.

In Toronto, about nine centimetres had accumulated by noon, and thousands of schoolchildren were given a snow day as classes were cancelled at all Toronto public and Catholic schools. The last widespread closure of public schools in Toronto occurred in January 1999, when the army was called in to help the city deal with a massive storm.

Public schools were also closed in Peel, Halton and Hamilton-Wentworth regions.

While public schools were still open in York and Durham regions early Wednesday, there was no bus service.

Vehicles on Toronto's Gardiner Expressway were held up near Jarvis Street as snowplows clear the roadway Wednesday morning. (Eric Foss/CBC)

A number of other institutions, including York University and the Scarborough and Mississauga campuses of the University of Toronto were also closed.

As of 1:30 p.m. ET on Wednesday, more than 340 flights out of Toronto's Pearson airport — roughly one-third of all those scheduled — were grounded, affecting thousands of passengers.

Travellers are advised to check with the Greater Toronto Airport Authority before heading to the airport.

All Porter Airlines flights out of Billy Bishop Toronto City Airport were cancelled before noon. Some afternoon Porter flights to Boston, Chicago and Newark, N.J., were also cancelled. There were no further cancellations on Porter flights to Canadian destinations.

Moving east

The storm is expected to track eastward through Kingston and Ottawa, into upstate New York later Wednesday and then to New England, Environment Canada said. The storm reached the Maritimes Wednesday afternoon.

A man clears snow on the sidewalk on Adelaide Street West near Bay Street in downtown Toronto early Wednesday. (Tony Smyth/CBC)

Although the storm fell short of expectations, it made driving difficult in the morning.

A stretch of the Gardiner Expressway between Kipling Avenue and Lake Shore Boulevard was reopened at around 7:30 a.m. after a two-hour closure due to downed hydro wires. There were no major public transit disruptions in the city.

Provincial police said "there are no good areas" along the snowbelt from Niagara Region in the south to Barrie in south-central Ontario.

Sgt. Dave Woodford said several vehicles slid off the snow-packed and icy roads.

While some London roads were closed, all 400-series highways remained open.

With files from The Canadian Press