According to the National Weather Service, frostbite happens when the body's survival mechanisms kick in during extremely cold weather. To protect the vital inner organs, the body cuts circulation to your extremities: feet, hands, nose, etc., which eventually freeze. To avoid frostbite, stay inside during severe cold, especially when the wind chill is -50°F or below. If you must go out:

• Cover every part of your body: ears, nose, toes and fingers, etc.
• Mittens are better than gloves.
• Keep your skin dry.
• Stay out of the wind when possible.
• Drink plenty of fluids since hydration increases the blood's volume, which helps prevent frostbite.
• Avoid caffeine, alcohol, and cigarettes. Caffeine constricts blood vessels, preventing warming of your extremities. Alcohol reduces shivering, which helps keep you warm. Cigarettes restrict the blood flow to your hands.

Here is a list of signs and symptoms for frostbite from the Center for Disease Control and Prevention.

What is hypothermia? Hypothermia is caused by prolonged exposures to very cold temperatures. When exposed to cold temperatures, your body begins to lose heat faster than it’s produced. Body temperature that is too low affects the brain, making one unable to think clearly or move well. While hypothermia is most likely at very cold temperatures, it can occur even at cool temperatures (above 40°F) if a person becomes chilled from rain, sweat, or submersion in cold water.

Here is a list of signs and symptoms for hypothermia from the Center for Disease Control and Prevention.