Choose the right bedding to provide the cat a warm place. Your first instinct might be to put down a fuzzy blanket in the cat shelter—but think again! Towels or blankets can actually absorb your cat’s body heat and make her colder. Also, any snow that your cat tracks into the shelter can also melt on a blanket, leaving kitty with an icy mess once the water refreezes.
Dry straw makes a good base for your cat’s shelter and will maintain heat better than blankets. Mylar is excellent (affordable and effective). Wrap it around a blanket or straw for padding. Inexpensive Mylar.
Straw is a great bedding choice for your winter cat shelter. It repels water and makes a comfortable cushion for cats. It’s important that you choose straw, not hay, which wicks away heat and retains water. For more information on the difference between straw and hay, take a look at this post from Alley Cat Allies.
Another way to keep your cat warm in her shelter is by providing self-warming cushions. Self-warming (mylar) cat bed.
To create a cat bed that is a bit warmer, place a cardboard box inside a plastic storage tub box, and stuff balled-up newspaper between the cardboard box and the plastic tub. This creates extra warmth.