I keep two of my three cats inside but a third white I took in after my dad died goes out at night as she gets stressed otherwise. During this cold snap I've kept her in a lot but yesterday couldnt get her in. At 2am I've gone to check and she's out there refusing to come in. I've left a cat shelter made if boxes and insulated with straw outside. Anyway, I cant get her in tonight and the real feel is - 4. She has a big fluffy coat. Everything I read says cats can get hypothermia in subzero temps, do you think she'll be ok? Will probably be able to keep her in tomorrow.