Winter shelters for feral/friendly cats to keep warm:

 

2 Rubbermaid containers 1 medium 1 small

Straw not hay

Owens corning sheet of insulation [Home Depot] [Lowes]

Measure and cut sheets of insulation to line the small container make a sm opening in both ends of container [this is to ensure the cat has an easy escape route]

Cut a small to medium opening in both ends of the medium [outside] container [escape route in case of a predator]

Line up sm cont inside the bigger one. Insulate the larger one really well with straw not leaving any air pockets

Than insulate the smaller one really well with lots of straw. Remember to leave a small gap in the front to ensure the cat can climb inside but will still keep the cold

Chill and wind from getting inside.