I did SERE school near Spokane during the early spring and it was already pretty miserable out in the woods. I literally can't imagine camping/living off-grid there during the winter lol. I think it would be hard mode personally, compared to a winter in like Arizona or something ;P
Camping and living are pretty different. Camping for a few days just requires the right gear and knowledge of using it. Living in a cabin, you'll probably want to have a wood stove that you keep fed and some warm blankets. Obviously (most parts of) Arizona in the winter are easier though water is a bigger problem there.
Pretty much what the other reply said: very damp and cold. Having lived in Spokane for a few years too the summers are also fairly brutal. That region has pretty extreme temperatures both ways.
From experience with the area, probably very wet, very little sun, and miserably chilly (not deathly cold, just the kind of ‘ughh this sucks’ wet-cold).
