Frostbite occurs when skin and other tissues are exposed to very cold temperatures. It can occur within minutes following exposure to extreme temperatures. Frostbite usually affects the hands, feet, nose, cheeks, and ears. Superficial frostbite injures the skin and tissues just beneath it, but usually does not permanently injure tissue. Deep frostbite, which also affects muscle, nerves, and blood vessels, may result in tissue death, a condition known as gangrene.