TORONTO — Flight delays and cancellations are still rampant out of Toronto, Ottawa and beyond as airports work to clear the backlog of flights from this weekend’s powerful ice storm.

The spring storm hit the U.S. Midwest before making its way up to Ontario and on to Quebec with record precipitation. Tens of thousands of people across southern and central Ontario are still without power today as the massive ice storm transitions to drenching rain.

Meanwhile Calgary is bracing for a month’s worth of snowfall in a single day.

The Greater Toronto Airports Authority (GTAA) has posted an advisory on its website, warning travellers to expect higher than normal passenger volumes early this week as passengers whose flights were cancelled begin travelling out of Toronto.

The storm played havoc with air traffic, with more than 600 flights cancelled at Toronto’s Pearson International Airport and many others delayed, often for hours.

Toronto’s downtown Billy Bishop airport cancelled all departing flights on Sunday and received only one arrival all day.

Porter Airlines has posted a weather advisory on its website for Toronto, Ottawa, Montreal, Sudbury, Quebec, Timmins, Sault Ste. Marie, Boston and Newark, effective April 16.

Air Canada has no fewer than 28 travel advisories for April 16 on its website, for Toronto, Ottawa, Timmins, Sudbury, Sault Ste. Marie, Montreal, Quebec City, Boston, New York and more, all for freezing rain, snow and ice storm conditions. “Air Canada has revised its ticketing policy for customers booked on affected flights to facilitate changes to bookings. Those customers wishing to make alternate travel arrangements can do so without penalty, space permitting.” Air Canada also has a travel advisory for Calgary.

The Western Alberta snow storm is also impacting WestJet, which has also issued a travel advisory with flexible rebooking optins for Calgary flights as well as flights in and out of Ottawa, Montreal, Boston and New York City (La Guardia).