We've just ordered an outdoor winter cat shelter for one. It's self-heating (!), it's slightly off the ground, it has a cat flap and a privacy window that can see out but not in. Wacky or what. It will sit next to our south-facing house wall in a very sheltered spot. We get light frosts only in winter and not many of them. We had three or four nights of-6C last winter, which was unusual. We've had cats for most of the last 45 years and they have always stayed out at night. No smelly litter trays for us. It's pretty safe for cats round here. We've always provided heated shelter for them, but this cat house is a first!