There are plenty of cancellations and delays in the winter not only because of an event at the airport you are at but also at other airports where there are delays that prevent inbound aircraft for your flight from arriving. If you are on Air Canada, then even if there is a delay of the inbound aircraft there are usually spares on the ground and substitutions can be made that provide an alternative. If it is an airline based elsewhere, then you have to wait for the scheduled flight to arrive, which may involve a longer delay. There are also outbound delays due to de-icing. You won't know until the day you travel what the real story will be. Weather forecasts are usually wrong.