Thank you for rescuing and taking care of the stray cat.
In so far as how cold is too cold: cats are survivors and know where to find the warm(er) places. Bushes, near buildings where there is some escaping heat. My cat survived a 20 inch snow storm before being rescued. I think it in part depends on how healthy the cat is, how well he is being fed.
You can buy discs that you microwave for around five minutes and are suppose to stay nice and warm for up to 10 hours. Some posters say the disks stay warm for ten hours, I found it to be less than that. You can place the disk any where, perhaps in a cardboard box, with a nice blanket in it near your house. Then she can decide to go in the box or not. I feed a feral cat colony and when possible, feed them warm food. Don't know if it helps keep them warm, but I like to think it does!
In so far as how cold is too cold: cats are survivors and know where to find the warm(er) places. Bushes, near buildings where there is some escaping heat. My cat survived a 20 inch snow storm before being rescued. I think it in part depends on how healthy the cat is, how well he is being fed.
You can buy discs that you microwave for around five minutes and are suppose to stay nice and warm for up to 10 hours. Some posters say the disks stay warm for ten hours, I found it to be less than that. You can place the disk any where, perhaps in a cardboard box, with a nice blanket in it near your house. Then she can decide to go in the box or not. I feed a feral cat colony and when possible, feed them warm food. Don't know if it helps keep them warm, but I like to think it does!