Like frostbite, frostnip is associated with ice crystal formation in the tissues, but no tissue destruction occurs and the crystals dissolve as soon as the skin is warmed.

The three stages are usually called frostnip, superficial frostbite, and deep frostbite. In stage 1 (frostnip), the skin reddens and then turns white. The area may feel numb. In the second stage of frostbite(superficial), the external layer of skin is frozen, but underneath is still soft. The area may appear grayish-yellow. In the final stage of frostbite(deep frostbite) the entire area is solid, and may appear grayish-blue.

Frostbite is the destruction of tissue due to exposure to very low temperatures.

If you are referring to Chilblains,

Its kind of like an allergic reaction to extreme cold, its usually occurs when Ice and other cold objects are placed in contact with the skin. It is often mistaken for frostnip or frostbite. It can cause itching, blisters, and inflammation.

Extreme cold weather can cause frostbite, frostnip and hypothermia, which is lethal. As well, some people suffer from 24 hours of sun during the periods without sunsets, and others suffer from 24 hours of no sun during the periods without sunrises.