Air Canada has issued a travel alert this morning.
A storm moving across southern Ontario and into the American northeast is expected to affect air travel operations for the rest of the day.
There are already flight cancellations and delays on the boards at Trudeau Airport and at Pearson Airport in Toronto.
Environment Canada has issued a snowfall warning for southern Ontario and the Toronto area is expected to get as much as 20 centimetres of snow by tonight.
Flights are also being cancelled In New York, Newark, Boston, Pittsburgh, Philadelphia, Baltimore and Washington.
FlightAware.com is reporting that 2000 flights have been cancelled within, into, or out of the United States today.