At 85 degrees, those freezing to death, in a strange, anguished paroxysm, often rip off their clothes. This phenomenon, known as paradoxical undressing, is common enough that urban hypothermia victims are sometimes initially diagnosed as victims of sexual assault. Though researchers are uncertain of the cause, the most logical explanation is that shortly before loss of consciousness, the constricted blood vessels near the body's surface suddenly dilate and produce a sensation of extreme heat against the skin.
The process of freezing to death is presented in horrifying detail in this classic article. It's not just a matter of getting cold and dying. For example, just before they freeze, people with hypothermia tear their clothes off in a fit of what's called "paradoxical undressing."