try to see the positive side: you can comfortably de-frost your freezer when it's so cold. You just put all the contents in a laundry basket and keep it outdoors overnight while the ice in your freezer melts. (1 cm = 2/5 inches ice doubles the freezer's use of electricity. The cold weather might help you save a few Pounds.)
And if you are near London: have a look at the German Christmas market at Hyde Park Corner. Just the thing to get into the Christmassy spirit!
(btw, -15°C are considered a warm noon in December/January over here in my part of Bavaria)
Btw, does anyone know what temperatures they currently have in Japan? It must be quite frosty there, too, at this time of year. Not a nice weather to wait outdoors for the earthquakes to stop.