I’m the original author of the envcanada Provider for the default Weather module. Environment Canada has made a significant change to their API and, for some reason, I never saw the notification they sent out a few months ago (I was supposedly on their mailing list). I’ve only taken a very brief look at their changes, so take my assessment with a small grain of salt:
The change has made it impractical to continue fetching an XML document for whatever location has been configured for weather info. They are, instead, pushing clients to a completely different API that is much more complex to use. The API is basically a pub/sub scheme that is based on the AMPQ protocol. How it all works and whether it will play nice within the MagicMirror ecosystem is still very much TBD.
Based on what I see, the envcanada Provider and MMM-EnvCanada will pretty much require total rewrites. I can continue poking at this but to be fully transparent, it will be a couple of months before I can give this any significant focused effort.