This can be done by slowly rewarming the affected part in a circulating water bath of 100-140 degrees Fahrenheit. This should generally be done for 20-30 minutes. Do not rub the affected area because this may traumatize the tissue and cause greater injury. If possible, seek medical attention immediately. Trenchfoot is another cold weather injury.
First aid includes cleaning, drying and slowly re-warming the feet.
And of course, seek medical attention as soon as possible. Hypothermia, or the lowering of the body's temperature to a point where normal body functions are impaired, can be deadly. Should you be placed in this situation, you must act quickly to save the person's life. Prevent further heat loss by providing warmth through blankets, coats or your own body heat. Act quickly and seek immediate medical attention.