As most of you in the UK will have noticed, it has been consistantly below freezing. A big concern during this type of weather is keeping your small furries warm, as they can go into hibernation if they get too cold, which is completely unnatural for hams and often leads to death.
I try to keep the temperature in the hammie room as a constant warmth, and give them extra bedding. If it gets really really cold I place a hot water bottle at the side or underneath the cage to keep them toasty.
If, heaven forbid, you find your ham hibernating then take them out of the cage and wrap them in a warm blanket or towel. They need warming up, but slowly, a huge change in temperature in a short space of time can also cause death. You could also wrap a hot water bottle in the towel and hold the hamster on that.