I can also add to the answer.
In the European Union, we see that many countries have very different geographical realities and climates. All sorts of airports are subject to very different circumstances. Yet they are all subject to the same regulations, which seems to work well.
As my colleague Mr. Charbonneau said, they are exempted only in extraordinary circumstances that arise through no fault of their own. So I do not see why, for the few flights to Canada's north, although I'm not an air transportation expert....
In my opinion, they are designed for the purpose, equipped differently, and have experienced pilots to deal with particular climate conditions. With the equipment and the experience, I think a two-hour delay would be the same as a delay in the south with equipment adapted to the specific temperature of the south. The regulations should simply include a fairly broad and clear framework, as is the case in the European Union.
I think the exemption for exceptional circumstances might be a good thing.