TORONTO — Air Canada has extended its extreme cold temperature alerts for Pearson Airport and Billy Bishop Toronto City Airport and added new extreme cold temperature alerts for Montreal-Pierre Elliott Trudeau International Airport and Ottawa Macdonald-Cartier International Airport, as the deep freeze continues. The airline is advising passengers that flights in and out of these airports may be impacted by strong wind conditions and subsequent Air Traffic Control restrictions.

Air Canada’s alert, effective so far for Jan. 2, Jan. 3 and Jan. 4, now applies to Pearson, Billy Bishop Toronto City Airport, Montreal-Pierre Elliott Trudeau International Airport and Ottawa Macdonald-Cartier International Airport. Earlier alerts were just for the Toronto airports.

The airline has revised its ticketing policy for customers booked on affected flights, to facilitate changes to bookings. Passengers wishing to make alternate travel arrangements can do so without penalty, space permitting.

Air Canada is reminding passengers to check their flight status before leaving for the airport, or call Air Canada’s automated flight information system at 1-888-422-7533.

WestJet has also extended its extreme cold warning alert, now effective through Jan. 2. “We advise all guests travelling to or from [Toronto] between Dec. 28, 2017 and Jan. 2, 2018 to check the status of their flights prior to leaving for the airport. Additional updates will be posted as they are available.”

The deep freeze is stretching into a second week for just about all of Canada and much of the U.S.