( mild) temps just touching -15C at night.
Nee wat jy is n hopeless case en jy het alreeds brain freeze opgedoen as -15 mild is!!! 
Jeez immigrant I would not be able to function in cold like that!! 
To be honest I thought the same before we moved here. But after hitting -16 the other day I must say it was not bad... Thing with it is this, in SA 0 outside is 0 inside. Here it is -16 out, but the buildings here are made to keep the heat in. So it was just 17 inside without the furnace going. Clothes also made for this winter. I only had jeans on the other day when it was so cold and could easily go from car to building without freezing.
Time will tell though. Winter has not hit hard this side of Canada yet. Andrew is on the front line...
Time spent in the cold and activity also play a big role.
Jeans, t-shirt and ski jacket was enough at -18C for about 30min but then we were walking between pubs.
Getting shoes and pants wet at 0C is also not a problem as they dry out in minutes when you are back in a warm building.
Spending time in a 10-15C house with tile floors without doing anything you soon start to feel the cold.