Here mid winter nights average -15c to -17c, days -3c to -7c not taking into account any wind chill factors.
We, being able to live off grid (if required) have no central heating or hot water system in the house instead we are set up with a petchka for heat and to cook on in kitchen/living area with log burners in bedrooms. These rooms also each have a plasma heater (if required). We have a log burning shower for further heat and hot water. If needed we have (stored in one of the cellars) a couple of calor gas heaters along with two oil filled radiators. Power can be supplied via either a gasoline generator or solar power battery power station.
Small winterizing things we do include:
Putting mats, rugs, skins down as extra floor insulation where as normally we have just the wood floorboards.
Replace the lightweight window and door (internal and external) drapes with heavy duty winter ones. Also we make use of draught excluders.
Bubble wrap the outside of certain windows that we have not repaired yet.
Insulate food stock racks in cold cellar to prevent stored and preserved food from freezing.
Breakout the wool blankets to be used as when required.
Empty and turn off the fridge freezer in the cold cellar as it stops working below a certain temperature.
Main thing for us working outside with livestock is keeping warm when on the go and as people have already mentioned, thermals, for us we have several sets of merino wool thermal tops/long johns and socks as a base layer. Rabbit fur ushankas to stop our head and faces from freezing. We also have wool ponchos and my partner knitted me a long sleeveless wool tunic that goes down to my knees (not for the fashion conscious) but absolutely brilliant for working in outside when it is freezing cold. We still have not found suitable gloves so combine what we have with hard warmers.
It sounds excessive but having been snowed and iced in on a regular basis without power and water you always need a variety of options.
Someone mention community on here which is a valid point. The village community centres/old peoples clubs that are in all villages here have wood stoves in and the village Baba's etc. meet, sit and talk in them nearly all day to keep warm. It also serves as a way to ensure no-one has died overnight as if someone does not arrive a youngster is dispatched to check on them (a youngster is normally some one in their 60's where as most Baba's are in their 80's!).