February arrived with a fury on Friday as southern and eastern Ontario got walloped with a day-long storm that was expected to dump as much 30 centimetres of snow in addition to freezing rain.

The storm began before the morning commute and was expected to last into the overnight hours.

More than 150 flights had been cancelled or delayed at Pearson International Airport in Toronto by noon, and several area school boards cancelled classes and buses. Colleges and universities also closed their campuses.

"This is a big storm system, so it's affecting other cities besides us," said Trish Krale, a spokeswoman with the Greater Toronto Airports Authority. "So that affects arrivals and departures."

Travellers were advised to check the status of their flight ahead of time.

See a list of closures here.

About 15 centimetres of snow is expected for Toronto, while the surrounding area could see 20 centimetres.

Environment Canada has issued a winter storm warning from Windsor to the Quebec border.

"Storm total snowfall amounts from a corridor from Bancroft to Ottawa could near 30 centimetres," reads a statement on the national weather service's website.

Blowing snow caused some whiteouts and made driving treacherous. Periods of freezing rain in the afternoon added to the tricky commute.

The precipitation, along with high winds, triggered provincial police to issue a warning to motorists to leave plenty of space between vehicles or stay off the roads altogether if possible.

Hundreds of accidents

More than 500 accidents had been reported to police by 5 p.m., mostly due to drivers sliding off roads or into guardrails. No serious injuries were reported.

One driver who lost control on Highway 400 was thankful he landed safely in a ditch.

"It was shaking right and left, and once that started happening I pretty much knew no matter what I did ... it still wasn't going to work, " the motorist said, admitting his vehicle didn't have snow tires.

Numerous tractor-trailers were getting stuck on slippery highway ramps, including two rigs that couldn't make it up the on-ramp from Kennedy Road to the westbound Highway 401.

OPP Sgt. Cam Woolley said in weather like this, drivers should avoid using their cellphones and pay extra attention to the road and driving conditions.

"If you do find your car starting to slide, look where you want to go, " he said. "Look for your escape route -- that's where your car will go."

Woolley assumed many residents were taking the day off work and staying home because the number of collisions was down compared to recent storms.

GO Transit said all of its buses were about an hour behind schedule, but all GO trains were operating normally.

The city of Toronto's entire fleet of snow-clearing vehicles -- 600 road plows, 200 salt trucks and 300 sidewalk plows -- were out on the streets all day Friday. Plows were to hit the roads again on Saturday.

Crews will focus on expressways and main arterial roads first before hitting local streets.

With reports from CTV Toronto's Galit Solomon and Alicia Kay-Markson