TBH, we/I don't like (read "operate"!) in anything like 10C or below (I just don't "function" unless there is a very definite need to be "outside" and with something active to do to keep my core body temperature up - FWIW, in my teens, I lived in a very old cottage that had no insulation in the roof and, at least on one occasion, I woke up in the morning to find my glass of water on the adjacent table was frozen - it was that cold in my bedroom then!). Nowadays, and over the intervening period, I have made sure that our house, which was
abominably cold some 40yrs ago, is as about as heavily insulated as possible - last night, and for most nights so far this Autumn/Winter, the most I have needed was a sheet and a couple of blankets!.
However, most of the people who live in colder climates are long-accustomed to "low" temperatures because that is what they are historically used to and they generally have already quite a lot of measures in place to make sure that the conditions in which they live (and sleep!) are OK - saunas and so on
. Maybe I could live with that - but I'm not sure that I want to try that, especially that dip in the snow afterwards (Yup, I'm rather "soft"!)!