If you work or play outside during the winter, you need to know how cold affects your body. Being active in the cold can put you at risk for problems such as hypothermia and frostbite.
How Cold Affects you
Cold temperatures, wind, rain, and even sweat cool your skin and pull heat away from your body. You also lose heat when you breathe and sit or stand on the cold ground or other cold surfaces.
In cold weather, your body tries to keep a warm inner (core) temperature to protect your vital organs. It does this by slowing blood circulation in your face, arms, hands, legs, and feet. The skin and tissues in these areas becomes colder. This puts you at risk for frostbite.
If your core body temperature drops just a few degrees, hypothermia will set in. With even mild hypothermia, your brain and body DO NOT work as well. Severe hypothermia can lead to death.
Dress in Layers
The key to staying safe in the cold is to wear several layers of clothing. Wearing the right shoes and clothes helps:
- Keep your body heat trapped inside your clothes
- Protect you from cold air, wind, snow, or rain
- Protect you from contact with cold surfaces
You may need several layers of clothing in cold weather:
- An inner layer that wicks sweat away from the skin. It can be lightweight wool, polyester, or polypropylene (polypro). Never wear cotton in cold weather, including your underwear. Cotton absorbs moisture and keeps it next to your skin, making you cold.
- Middle layers that insulate and keep heat in. They can be polyester fleece, wool, microfiber insulation, or down. Depending on your activity, you may need a couple of insulating layers.
- An outer layer that repels wind, snow, and rain. Try to choose a fabric that is both breathable and rain and wind proof. If your outer layer is not also breathable, sweat can build up and make you cold.
You also need to protect your hands, feet, neck, and face. Depending on your activity, you may need the following:
- Warm hat
- Face mask
- Scarf or neck warmer
- Mittens or gloves (mittens tend to be warmer)
- Wool or polypro socks
- Warm, waterproof shoes or boots
The key with all of your layers is to take them off as you warm up and add them back as you cool down. If you wear too much while exercising, you will sweat a lot, which can make you colder.
Get Plenty of Food and Fluids
You need both food and fluids to fuel your body and keep you warm. If you skimp on either, you increase your risk for cold weather injuries such as hypothermia and frostbite.
Eating foods with carbohydrates gives you quick energy. If you are only out for a short time, you may want to carry a snack bar to keep your energy going. If you are out all day skiing, hiking, or working, be sure to bring food with protein and fat as well to fuel you over many hours.
Drink plenty of fluids before and during activities in the cold. You may not feel as thirsty in cold weather, but you still lose fluids through your sweat and when you breathe.
Watch for Early Signs of Frostbite and Hypothermia
Be aware of the early signs of cold weather injuries. Frostbite and hypothermia can occur at the same time.
The early stage of frostbite is called frostnip. Signs include:
- Red and cold skin; skin may start to turn white but is still soft.
- Prickling and numbness
Early warning signs of hypothermia include:
- Feeling cold.
- The "Umbles:" stumbles, bumbles, grumbles, and mumbles. These are signs that cold is affecting your body and brain.
To prevent more serious problems, take action as soon as you notice early signs of frostbite or hypothermia.
- Get out of the cold, wind, rain, or snow if possible.
- Add warm layers of clothing.
- Eat carbohydrates.
- Drink fluids.
- Move your body to help warm your core. Do jumping jacks or flap your arms.
- Warm up any area with frostnip. Remove tight jewelry or clothing. Place cold fingers in your armpits or warm a cold nose or cheek with the palm of your warm hand. DO NOT rub.
When to Call the Doctor
You should call your health care provider or get medical help right away if you or someone in your party:
- Does not get better or gets worse after attempting to warm up or to rewarm frostnip.
- Has frostbite. NEVER rewarm frostbite on your own. It can be very painful and damaging.
- Shows signs of hypothermia.
Centers for Disease Control and Prevention website. National Institute for Occupational Safety and Health. Fast facts: protecting yourself from cold stress. www.cdc.gov/niosh/docs/2010-115/pdfs/2010-115.pdf. Accessed November 24, 2022.
Gómez JE, Chorley JN, Martinie R. Environmental illness. In: Miller MD, Thompson SR, eds. DeLee, Drez, & Miller's Orthopaedic Sports Medicine. 5th ed. Philadelphia, PA: Elsevier; 2020:chap 21.
Zafren K, Danzl DF. Hypothermia, frostbite and nonfreezing cold injuries. In: Walls RM, ed. Rosen's Emergency Medicine: Concepts and Clinical Practice. 10th ed. Philadelphia, PA: Elsevier; 2023:chap 128.
Review Date 8/11/2022
Updated by: Linda J. Vorvick, MD, Clinical Professor, Department of Family Medicine, UW Medicine, School of Medicine, University of Washington, Seattle, WA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.