When the temperature dips and the wind whips, your body goes into overdrive to keep your core body temperature stable. That's when your extremities and exposed skin -- as your cheeks, nose and ears -- become vulnerable to frostbite. If you begin to feel numb or a stinging sensation, head indoors and slowly warm (but don't rub) the affected area. If numbness continues, seek medical care. Excessive shivering, sluggishness and confusion are signs of hypothermia, which is a medical emergency.