Cold Weather Exercise: How Cold Is Too Cold Outside?

Cold weather exercise works if you dress in layers and watch the wind chill. The National Weather Service says exposed skin can freeze in 30 minutes at a wind chill of -19°F. Mayo Clinic says air temperatures below 0°F or extreme wind chills may make outdoor activity unsafe.

Published October 23, 2026.

This article is general information, not medical advice. Cold can strain the heart and lungs, and it can cause frostbite and hypothermia. Talk with your doctor first if you have a heart, lung or circulation condition. Do the same if you are unsure that outdoor exercise is safe for you.

I live in Colorado, so cold-weather workouts are a yearly decision for me. My habit is to settle the limits before the workout starts, not at the door. The limits in this guide come from the charts and sources named below.

When Does Cold Weather Exercise Stop Being Safe?

There is no single temperature, but two lines are worth knowing. In a March 2023 Q and A, Dr. Kelechi Okoroha of Mayo Clinic orthopedic surgery says air temperatures below zero F may prohibit safe activities outside. Extreme wind chills can do the same. The same piece says the risk of frostbite significantly increases when the air temperature is below 5°F.

Wind changes the picture. Per the National Weather Service (NWS), wind chill is based on heat loss from exposed skin caused by wind and cold. It is defined only for temperatures at or below 50°F and wind speeds above 3 mph. Because it tracks exposed skin, it matters most for the cheeks, nose, ears, hands and feet. Mayo Clinic Health System names the cheeks, nose and ears as most at risk for frostbite.

One more NWS rule keeps the numbers honest. Frostbite needs the actual air temperature to be below freezing. A windy day above freezing can leave you cold. The agency says wind chill alone cannot cause frostbite at those temperatures. Hypothermia is still possible.

How Do You Read the NWS Wind Chill Chart?

The NWS chart shades its frostbite times in three bands: 30, 10 and 5 minutes. I read the sample rows below from the chart. Then I recomputed each wind chill with the NWS formula. Here it is: 35.74 + 0.6215T – 35.75(V^0.16) + 0.4275T(V^0.16). T is air temperature in °F, and V is wind speed in mph.

Here is the arithmetic for the 0°F, 15 mph row. Fifteen raised to the 0.16 power is about 1.542, and 35.75 times 1.542 is 55.14. The two terms with T drop out because T is zero. That leaves 35.74 minus 55.14, or -19.4, which rounds to the chart’s -19°F. It matches the NWS statement that exposed skin can freeze in 30 minutes at that wind chill.

Mayo Clinic Health System athletic trainer Corey Wencl draws the same line in a February 2023 article on cold-weather training. Below a wind chill of minus 18, he writes, frostbite can occur on exposed skin within 30 minutes or less. The chart’s times apply to exposed skin, so a 5-minute row at -64°F is a day for the gym.

How Does Cold Weather Exercise Affect Your Heart?

Cold air makes the heart work harder. The American Heart Association (AHA) says cold air constricts blood vessels throughout the body. That raises blood pressure and tightens the coronary arteries. Barry Franklin, Ph.D., directs preventive cardiology and cardiac rehabilitation at Corewell Health East. In a January 2024 AHA release on snow shoveling in the cold, he said “you’re asking your heart to do a lot more work.”

The AHA wrote those releases about snow shoveling, but the line about cold air describes blood vessels in general. Its advice carries over to any winter workout. Start gradually and pace yourself. Cover your mouth and nose, wear layers, and put on a hat and gloves. Stop immediately if you feel chest pain or pressure, lightheadedness or heart palpitations. Call 9-1-1 if symptoms do not subside shortly after you stop.

Lungs and circulation matter too. Okoroha says cold weather may aggravate exercise-induced asthma. People with Raynaud’s disease, lung or heart disease or lupus should consider consulting their primary care team about precautions. If any of those describe you, get your own limit from your doctor before you rely on the chart above.

What Should You Wear for Cold Weather Exercise?

Wear three layers and skip cotton. Wencl describes a thin synthetic base layer, such as polypropylene, that draws sweat away from the body. Next comes a fleece or wool layer to hold in warmth, and a waterproof, breathable layer goes on top. Okoroha says to avoid cotton against the skin because it can stay wet and cold. Wencl’s check is simple. A little chill at the start of your warm-up means you have probably layered correctly.

Hands, head and feet need their own plan. Wencl recommends thin glove liners of a wicking material under heavier gloves or mittens lined with wool or fleece. Then you can take off the outer pair when your hands get sweaty. He also lists a hat or headband and thermal socks. He adds that running shoes one size larger may be needed to fit the thicker socks. The AHA adds that you should cover your mouth and nose.

Rain changes the rules. Okoroha says to avoid exercising in the rain, because getting wet increases your vulnerability to the cold. MedlinePlus lists wet clothing in wind or cold among the causes of hypothermia.

How Should Layers Change With the Temperature?

This table turns those sources into bands. Each limit comes from a source: 50°F where NWS wind chill begins, 32°F for freezing, and 5°F and 0°F from Mayo Clinic. Mayo Clinic Health System supplies the -18°F line. The clothing columns are my own starting point, not a published standard, built on the three-layer system Wencl describes. Use the NWS wind chill as your “feels like” number when there is wind. With no wind, use the air temperature.

How Do You Warm Up for Cold Weather Exercise?

Double the warm-up. The Mayo Clinic Q and A says to double the warm-up in the cold, because muscles take longer to acclimate. Do the aerobic part first and ramp up slowly. Save static stretching for after that part. Finish with a cooldown, which the piece says promotes recovery and reduces blood pooling.

That lines up with the AHA advice to start gradually and pace yourself. Keep the first few minutes easy and close to shelter. For an indoor start, I wrote a 10-minute mobility routine for stiff mornings. You can run through it before heading out. Training for a first race this winter? Here is a beginner’s guide to running a first 5K. More routines live in the Fitness & Exercise section.

What Are the Signs of Frostbite and Hypothermia?

What Does Early Frostbite Feel Like?

Numbness is the first thing to act on. Mayo Clinic Health System lists numbness, loss of feeling and a stinging sensation as early frostbite signs. The cheeks, nose and ears are most at risk, and the hands and feet can be affected too. The CDC says redness or pain in any skin area may be the first sign. Other signs include a white or grayish-yellow skin area, skin that feels unusually firm or waxy, and numbness. Frostbitten tissue goes numb, so people often do not notice the injury.

If you notice any of this, get out of the cold and warm the area slowly. Wencl says not to rub it, because rubbing can damage the skin. Get emergency care if the numbness does not go away.

When Is Hypothermia an Emergency?

Hypothermia is a different problem. MedlinePlus defines it as a dangerously low body temperature, below 95°F (35°C). Its symptom list includes confusion, drowsiness, pale and cold skin, slowed breathing, weakness and loss of coordination. It also lists shivering that cannot be controlled. The CDC lists shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech and drowsiness for adults.

MedlinePlus says to call 911 or the local emergency number anytime you suspect hypothermia. While you wait, move the person indoors or out of the wind and replace wet clothing with dry clothing. In severe cases, move the person with as little exertion as possible. Do not use direct heat such as hot water or a heating pad, and do not give alcohol. MedlinePlus also names heavy exertion and not eating or drinking enough in cold weather among the causes. Keep fuel and fluids with you.

Should You Still Hydrate During Cold Weather Exercise?

Yes. The Mayo Clinic Q and A says hydration matters as much in the cold as in warm weather, or more. Water or a sports drink covers a workout of an hour or less. Longer sessions call for a drink with electrolytes, and the piece says to hydrate before, during and after. For the electrolyte side, see this runner’s guide to electrolytes.

What Else Do People Ask About Cold Weather Exercise?

Is it safe to exercise outside below zero?

It can be unsafe. The Mayo Clinic Q and A says air temperatures below zero F or extreme wind chills may prohibit safe activities outside. Frostbite risk rises significantly below 5°F. Mayo Clinic Health System suggests a break or an indoor workout below zero. It says the same for extreme wind chill or poor visibility from snow. Moving the session indoors is the safer default.

What should you do if your fingers or nose go numb outside?

Get out of the cold and warm the area slowly. Mayo Clinic Health System lists numbness, loss of feeling and a stinging sensation as early frostbite signs. The cheeks, nose and ears are most at risk, and the hands and feet can be affected too. Do not rub the skin, because that can damage it. Seek emergency care if the numbness does not go away.

Can you exercise outside in the cold with asthma or heart disease?

Ask your doctor first. Mayo Clinic says cold weather may aggravate exercise-induced asthma. People with lung or heart disease should consider consulting their primary care team about precautions. The American Heart Association says to stop immediately if you have chest pain or pressure, lightheadedness or heart palpitations.

Is it okay to exercise outside in cold rain?

Mayo Clinic advises against it. Getting wet increases your vulnerability to the cold. MedlinePlus lists wet clothing in wind or cold as a cause of hypothermia. Mayo Clinic Health System’s three-layer advice includes a waterproof, breathable outer layer. Even so, a cold rain is a good day to move indoors.

Should You Exercise Outside When It Is Cold?

I would exercise outside in the cold when the wind chill is above -18°F. I would also want three layers on and a way to get indoors within minutes. That puts the Mayo Clinic Health System frostbite line and the three-layer advice into one rule I can follow. Below 0°F, or any time the NWS chart shows a shaded band for your conditions, the workout moves inside.

Anyone with a heart or lung condition should get a personal limit from a doctor before using any chart. Indoor days still count. A routine you can keep all winter beats one heroic run at -20°F.