According to the Centers for Disease Control and Prevention, the areas most often affected by frostbite are usually the ones with the most exposure to the cold.

Frostbite is essentially your body tissue freezing.  And depending on the temperature, frostbite can happen in the matter of minutes or during prolonged exposure.

According to chicago.cbslocal.com, those most at risk are young children, smokers and diabetics.  While people may think drinking alcohol will keep them warm, it has the opposite effect.  Alcohol lowers the core body temperature and increases the risk of frostbite.

In general people should remember to wear multiple layers, and cover their faces, heads and hands to stay safe.  To read about frostbite symptoms from CDC, please click on the above link.