Welcome!
There are a number of us who live in the northern US and Canada, and the weather has been a topic of some conversations. As far as I know, the main thing you need to concern yourself with is a proper foundation so that you're protected from the effects of frost heave.
There are two options in this case. One is a deep foundation, where you dig below the frost line, pour a footing, and build a foundation wall up to grade. Your slab rests on that wall. Look for recent photos from mfiore and dbhansen to see some examples of this.
The other option (which I am considering here in Iowa, where the recommended depth for footings is 48") is what's called a frost-protected shallow foundation. Not a lot of builders on this site have done this, but it is more or less the approach used in the Alan Scott oven plans. A good explanation of the method can be found
here; the last diagram is especially relevant to ovens.
Ed