Cold, wet, windy, snow. All things you will deal with.
So, make a coop and run with your weather in mind. You will also expand and contract your flock now and again. Plan for up to 16-20 bc this may occur, even if only for a few months. We overlap chickens - we get new in Feb, get rid of in Oct/Nov depending on age, bird, plans for next year. My kid shows chickens in 4H, so the categories and rules for that do impact our flock decisions. We like to get the great egg laying months to our benefit, so don’t sell until the fall, and keep several chickens and at least one male over winter. We have 4 from original flock we’ve promised can stay until they die, so that is also a part of our plan (whether they lay eggs or not).
Ventilation: keep eaves open and elevated above the coop walls-easy way to get year round ventilation above head of the chickens. Roof vents, helpful, but if you do a single slant roof, might not need that. Don’t rely on on windows bc in the winter you will close them at times. If you add windows and want them open much of the year, place them away from the roosts, or where the roosting chickens won’t be in a draft.
Wet/rain/runoff: an issue? Make sure it’s not. Otherwise dig ditch, build berm, etc. elevate the coop: we did this, ours is an elevated walk-in coop that is elevated 2.5 feet above the ground, and it was an excellent choice for us.
Ice/ frozen doors: do yourself a favor and make sure to build in a decent overhang or all out 3-6’ of roof over your entry door. Don't have it face your predominant winter wind direction.
Good luck! Enjoy your chicks!