The signs of frostbite include an initial cold and prickling sensation, followed by numbness and then red, white, blue-white or yellow-gray skin color, according to the Mayo Clinic. The skin may also appear hard or waxy, and there may be blistering after rewarming in severe cases.
There are several stages for frostbite, the first of which is called frostnip and consists of pale or red, numb skin with possible pain upon rewarming, according to the Mayo Clinic. Frostnip does not cause permanent damage. The next stage is superficial frostbite, in which ice crystals form in the tissue. The skin may begin to feel warm, which indicates serious damage. Severe or deep frostbite begins to affect deeper tissues and may cause large blisters one to two days after rewarming, and the area may turn black and hard due to death of the tissue.