Canada airport codes - not always Yxx?

[jabird]

I thought all airport codes in Canada had a Y prefix, but note that Coal Harbour in Vancouver is CXH.

Looking at an airport codes date base, I see there are quite a few others, and that there are also 30 or so airports outside Canada with a Y prefix. So is the "Y" a generalisation (originating from the Canadian rail system?), rather than any kind of "rule" Canada has a "right" to?

[The SSK]

Canada has lots of Xs and Zs as well. And at least one W

[Cyrano]

Jabird:

Seems the question's been asked before, over here . Not sure how authoritative the answers are, but it seems to hinge on weather stations and radio callsigns.

[Jason Itterman]

Canadian Airports with a Y designation signify that there is a Weather station there.