Answer:
Not a very clear question, as this obviously depends on a number of factors, not the least of which is how cold the environment is. Other conditions which affect the development of frostbite include weather conditions, altitude, degree of protective clothing, duration of exposure, degree of tissue wetness. Sensory nerve activity is abolished at skin temperatures of 7-9 degrees celsius, so that the disappearance of pain is an early warning sign of cold injury. Previous history of frostbite, smoking, and PVD also limit cold tolerance (from Greenfield, Surgery: Principles and Practice).