A major winter storm bearing down on Toronto is adding to the calamity in Canadian airports already plagued by flight cancellations and delays set off early this week by heavy snow in Vancouver. 

Environment Canada says Toronto's storm will begin today with rain or snow followed by plummeting temperatures, a potential flash freeze and blizzard-like conditions Friday.

Toronto's Pearson International Airport has cautioned it could affect operations, while Environment Canada warns of possible extensive power outages and dangerous travel conditions.

It follows days of heavy snow and extreme cold in Vancouver that severely impaired airport operations, prompting the airport to halt all incoming international arrivals until Friday morning so congestion on the tarmac could be cleared. 

While there was some reprieve in Vancouver Wednesday, the airport says it's doing everything in its power to prepare for more severe weather today and pledges to provide detailed information before the system arrives.

Hundreds of Air Canada and WestJet flights have been grounded since Sunday and other affected airports include those in Victoria and Calgary.

This report by The Canadian Press was first published Dec. 22, 2022.