When I first thought about moving to Japan I never thought about the weather. My students/friends told me that it was humid in the summer (which holy crap it is....that is another story) but I was told the winters are mild and nothing like what I was used to in Canada. That much is true.
The first winter I swear I only wore a sweater and most of the time I was ok. What they didn't tell me is that even though it does get below zero occasionally and it is cold enough to snow 2 or 3 times in a season, there is no central heat. This is a big deal. My first few winters, I was fine outside but freezing inside. They don't have central heat but they do have other heaters and ways to stay warm but I have to say that when you are used to central heat and every room being basically the same temperature, it just isn't the same. I would be at home freezing, air conditioner on (air conditioners are also heaters), blanket on and still cold. I would be sitting there wondering "why is my nose cold? I'm inside...this isn't right!"
The first winter I went to a friend's house. Her family (like many if not most) used a "kotatsu". A "kotatsu" is an electric table. It consists of a table with an electric heater attached to the underside of the table. The kotatsu is usually set on a thin futon, like a throw rug. A second futon, this one thicker, like a comforter, is placed over the kotatsu table, with the table top placed on top of that futon. The electric heater attached to the underside of the table heats the space under the comforter, and anyone who happens to be snuggled under it.It gets pretty toasty under there. This family also used a "hot carpet" so I'm sitting on the hot carpet and my lower half is sitting under the table....I was hot and cold at the same time. My a$$ felt like it was on fire and my nose felt like an ice cube!!!
Now....maybe you think that isn't so bad....now imagine being naked in the bathroom with no heat and in many cases air seeping through cracks and crevices or in some cases windows wide open---in December---and it's snowing outside!!! Shocking!!!
I've had friends say that in the mornings they can see their breath. I haven't experienced that but sometimes it is colder in my apartment than it is outside.
Now I am used to it and don't mind it and in fact I have problems when I go to Canada in the winter. I wake up sweating in the middle of the night since I'm not used to a warm room and warm blankets.
It sure is amazing what you can get used to!!