I'm too lazy to do it through mod.. so I'm accumulating data slowly via hunting
These are the collected Warmth values (only furs of course, no leather):
Stag/Reindeer/Elk: 5
Bear/Sheep/Ram: 4
Wolf/Arctic Fox/Badger/Grey Seal/Glutton: 3
According to the figure above, Arctic fox should be a 5 (I wouldn't devalute the "deers", since real-world northern tribes, inuit included, use those in winter - so not sure what's going on with the plot), wolf should join bear/sheep (I don't know if finland sheeps are "dall sheeps", let's assume not).
The normal fox is fine as a 3 (I'm assuming is the same), but the arctic definitely not - especially considered how valuable it is, and how small it is. You'd need a load of foxes for that overcoat!
I'd only make a-fox mittens and footwear probably, with a hood of wolf