Every winter, cats die due to being left outside in the cold. That they have fur does NOT ensure their ability to survive out of doors for any length of time when the thermometer plummets.
What they DO need is shelter and warmth. And if your precious puss slips outside unseen, she must be found as swiftly as paws-ible or hypothermia will set in.
Hypothermia is the extreme lowering of a cat’s body temperature when she’s either been exposed to frigid conditions for too long or if her fur has gotten wet in the cold and the wind. This drop will cause her heart rate and breathing to slow down, and the results of sustained, severe hypothermia can include frostbite, neurological problems (including coma), heart problems, kidney failure, cessation of breathing, and ultimately death.