Guinea pigs are most comfortable at ambient temperature between 62 and 68 degrees farenheit. Any lower and they can catch a chill. Any higher and they could suffer heatstroke. This is why it's best to keep them indoors when it's cold out. GPs also like being away from the noise of a busy house, and away from other, inquisitive (or hungry!) pets such as cats and dogs.
Guinea Pig Illnesses Linked To Temperature
If your guinea pig is wheezing, has a runny nose or makes any obvious noise when it breathes, take it to the vet. It may have developed an allergy or caught a chill. In hot weather, if the guinea pig is lying down a lot, or panting (breathing fast with mouth open), it’s probably overheated, and may even be suffering heat stroke. In these circumstances the GP needs to be sprayed with cool water (not ice-cold, though) and left in a cool place to recover. If they’re still panting after another half an hour, apply more water.
If keeping guinea pigs indoors, you'll need to regulate the room temperature
A spare room, or one with little human traffic, is an excellent place to set up the guinea pig hutch. The room mustn't be drafty, dusty, or damp, though. This is why garages and laundry rooms aren’t always the best places, in spite of their obvious appeal. Guinea pigs need to be kept away from toxic fumes, drafts, chemicals, and temperature fluctuations.
Guinea pigs can easily develop upper respiratory tract infections if exposed to cold drafts, and they don’t do well in high humidity either, or if the temperature goes up and down frequently. This is simply because in the wild they’re used to the temperature changing much more slowly from day to night, and they only have very basic heating and cooling mechanisms of.
If the guinea pigs are going to be indoors for long periods, they still need space to exercise in. If you have an Eglu Go Guinea Pig Hutch, they can simply run around in the run section of the enclosure. If you don’t have one of these, you can make your own exercise enclosure or buy one. Make sure it's safe and secure!
Guinea pigs living outside need shady areas to keep cool in. If it goes above 78 degrees farenheit, the GPs will need to be brought indoors and allowed to cool down. The run will need a nice shaded area to allow the guinea pigs to escape the sun. They can get sunburnt, just like light-skinned humans, and don’t enjoy being trapped outside in unrelenting heat. They can’t sweat to cool themselves down, so always keep an eye on the temperature.
In the winter, some owners put their run at the side of the house so that it’s sheltered from wind, and protected from the worst of the rain. It’s best not to let guinea pigs out on wet grass, as this can put them at risk of catching pneumonia. If you have a wooden hutch, you’ll need to make sure it doesn’t get damp and give your guinea pigs a potentially fatal chill.
Guinea Pigs in Sheds
If you want to put your guinea pigs in the shed, it will need to be warm in the winter (you will probably need to use a heater) and properly ventilated in the summer. If the shed is dry and falls within the 62 and 68 degrees range, your guinea pigs will be fine in there, although they might prefer to have their run outside in the summer so that they can enjoy running around in the fresh air.