Put tons of straw or hay into the hutches/cages. Maybe a blanket or two, and if you want to, put a stuffed animal in there with them. Is there a way for wind to get in? Could you send a picture of the hutches/cages to let us know what they look like? If there is a way for wind to get in, put up plastic window sealer that is for outdoor use. Make sure the water bottles don't freeze. It would be best if you can bring them (the rabbits not the water bottles
) indoors, but totally understand if you can't since my rabbit is also not allowed indoors. Check out the link below for how to keep rabbits warm in the winter.
https://www.thecapecoop.com/getting-rabbits-ready-for-winter/