although it would be ideal if the guinea pigs cage could be moved into a shed or conservatory for the winter months. If you have no choice but to leave your guinea pigs hutch outside then when its very cold and frosty its a good idea to hang an old carpet over the wire mesh of the hutch as a little piece of protection. Do not use plastic though as this can lead to condensation which will cause the bedding in the hutch to become wet and the cavies will get chilled.
However throughout the day please make sure that your guinea pigs have some daylight and fresh air. If they have dry bedding placed in their hutches, their coats will become thicker to provide extra warmth during the colder months of the year. Their hair is very warm and even though it may feel cold on top to touch, if you burrow down to the skin the temperature can feel very comfortable.
Guinea Pigs are more suseptible to draughts than cold so make sure the guinea pigs hutch is moved out of wind in a sheltered area. You know how uncomfortable it can be sitting in a draught in your living room and a guinea pig will feel just as uncomfortable if there is one in his hutch.