Straw/hay works as a really good insulate for cats, dogs, horses, etc.

I know how you feel Gary. I worry about Oliver outside at times like these. He came for his food this morning and when he meowed the steam came from his mouth. Oliver has a doghouse with 2 layers of flannel blankets, a self heating pad (it warms itself when the cats lay on it) and then I also put out 3 heated SnuggleSafe discs that are heated in the microwave (they give off heat for 12 hours).

My thoughts and prayers are with your porchies.