Different Degrees of Frostbite
First degree: ice crystals forming on your skin
Second degree: your skin begins to feel warm, even though it is not yet defrosted.
Third degree: your skin turns red, pale, or white.
Fourth degree: pain lasts for more than a few hours, and you may see dark blue or black areas under the skin. See a doctor immediately if these symptoms arise. Gangrene is a real threat.