In advance of the coming storm, I extended and reinforced the feral shelter

[Warpy]

13. Maybe either army surplus or thrift shop blankets or bedspreads

could be tacked across the front in winter, anything to break the chilly wind. Disadvantage: you won't be able to see who's in there without a trip out into your cold yard with a flashlight. You can flip the covering up and out of the way when the weather is a bit milder.

And if they turn into little furry fusspots who won't use a more enclosed space, the capital outlay was low and it's easy to take it off. My guess is that they'll appreciate any sort of a wind break.