The short answer: dress as if it's about 20°F warmer than the thermometer says. Sports medicine physicians and university running specialists give this rule. You should feel a little chilly for the first few minutes, because running heats you up fast. Wear a thin moisture-wicking layer next to your skin, not cotton. As the temperature drops, add an insulating layer and then a wind-resistant shell. Protect your hands, ears and face early, because they get cold first.
The 20-degree rule, and why you should start cold
Running produces a lot of body heat, so clothes that feel right at your front door will feel too warm 10 minutes later. Dr. David Smith of the University of Kansas Health System puts it this way: dress "as if it were 20 degrees warmer than the true outdoor temperature." He also advises layering "but do not overdo it." Dr. Aaron Gray, a sports medicine physician at MU Health Care, gives the same rule, and so do Drexel's running specialists, who add that you should expect to feel a bit cold at the start.
Overdressing isn't just uncomfortable. Extra layers make you sweat, and wet clothing pulls heat away once you slow down or the wind picks up. The CDC notes that hypothermia can occur even at cool temperatures above 40°F (4°C) if a person is chilled by rain, sweat or cold water.
What to wear running in cold weather, by temperature
| Temperature | Top | Bottom | Hands, head and feet |
|---|---|---|---|
| 50s°F (10 to 15°C) | Short- or long-sleeve wicking shirt | Shorts | Usually nothing extra. Light gloves are optional on a windy morning. |
| 40s°F (4 to 9°C) | Long-sleeve wicking shirt, plus a light vest or jacket if it's windy | Shorts or light tights | Light gloves and a thin hat or headband |
| 30s°F (−1 to 4°C) | Long-sleeve wicking base layer under a long-sleeve shirt, light fleece or vest | Shorts, running pants or tights | Light gloves and a hat |
| 20s°F (−7 to −2°C) | Long-sleeve base layer under a thicker fleece or jacket | Running tights, with pants over them if needed | Mittens, a hat and warm moisture-wicking socks |
| 10s°F (−12 to −8°C) | Base layer, an insulating middle layer and a wind-resistant jacket | Tights under wind-resistant pants | Mittens, a balaclava or face covering, moisture-wicking socks and dark sunglasses |
| Below 10°F (−12°C), or a wind chill near 0°F (−18°C) or lower | Everything from the 10s row, with no exposed skin | Tights under wind-resistant pants | Cover your face, ears and hands completely. Consider a short loop near home, or run indoors. |
The rows for the 30s, 20s and 10s follow the examples Drexel's Running Performance and Research Center published for 30, 20 and 10 degrees. At zero degrees, its advice is simply "Run inside!" The 40s and 50s rows apply the same 20-degree rule: a 50°F run feels like a 70°F one once you're moving. Nobody tested these outfits for this article. Use them as a first guess and adjust after a run or two.
A few adjustments help:
- Wind: Dress as if it were one row colder, or add a wind-resistant outer layer. Dr. Gray notes that cold wind on sweaty skin quickly lowers skin temperature. He suggests windproof clothing or routes with natural windbreaks.
- Sun: According to the National Weather Service (NWS), bright sunshine can raise the wind chill by 10°F to 18°F, so a sunny day can feel a row warmer.
- Rain or wet snow: Wet clothing speeds heat loss. Choose an outer layer that sheds water, and keep the run shorter if you can't stay dry.
- Pace: Hard workouts make more heat than easy runs. For an easy run, a long run or a run with walk breaks, dress a little warmer.
- You: Some people run cold. Note what you wore and how it felt, and you'll soon have your own version of this table.
How to layer: base, insulation, shell
Layers let you match your clothing to the conditions, and you can take one off during the run. The NWS advises dressing in layers of loose-fitting, lightweight, warm clothing, and the CDC's National Institute for Occupational Safety and Health (NIOSH) points out that tight clothing reduces blood flow to the hands and feet. For running, each layer has its own job:
- Base layer, to move sweat: A thin, moisture-wicking fabric next to your skin. Dr. Smith recommends a wicking base layer rather than an absorbent material like cotton. Cotton soaks up sweat and stays wet, which is exactly what you don't want once you slow down.
- Middle layer, to insulate: A long-sleeve shirt or light fleece in the 30s, and a thicker fleece in the 20s and below. Skip it on milder days.
- Outer layer, to block wind and wet: A wind-resistant jacket, plus wind-resistant pants in the teens and below. Drexel's specialists suggest zippered pieces, so you can let heat out without stopping.
The CDC lists the nose, ears, cheeks, chin, fingers and toes as the areas frostbite most often affects. The NWS advises that mittens are better than gloves, which is why the colder rows of the table switch to mittens. Choose socks that keep your feet warm without squeezing them. Dr. Smith also notes that cold can stiffen the rubber soles of running shoes. If you're buying a new pair before winter, our guide to choosing running shoes for flat feet covers fit and support.
Wind chill: check it before every winter run
The NWS wind chill index estimates how cold it feels on exposed skin when wind speeds up heat loss. It applies when the temperature is at or below 50°F and the wind is faster than 3 mph. A few readings from the official NWS wind chill chart:
- 30°F with a 10 mph wind feels like 21°F.
- 20°F with a 15 mph wind feels like 6°F.
- 0°F with a 15 mph wind feels like −19°F. At that wind chill, exposed skin can get frostbite in 30 minutes.
At colder or windier combinations, the chart's frostbite time drops to 10 minutes and then to 5 minutes. The American College of Sports Medicine (ACSM) position stand on preventing cold injuries during exercise recommends using the wind chill index to estimate frostbite risk. It calls for closer monitoring of exercisers when the wind chill falls below −18°F (−27°C).
The NWS also clears up a common myth: frostbite needs the actual air temperature to be below freezing, so wind alone can't freeze your skin on a 40°F day. Hypothermia is still possible at those temperatures, though. Check the wind chill along with the temperature. On a windy day, consider heading out into the wind and coming home with it at your back. That way you aren't facing a cold headwind at the end, when you're sweaty and tired.
Cold-weather running safety
Know the warning signs of frostbite
According to the CDC, redness or pain in any skin area may be the first sign of frostbite. Later signs include a white or grayish-yellow patch of skin, skin that feels unusually firm or waxy, and numbness. Because the area goes numb, people often don't notice frostbite until someone else points it out. If you see these signs, get indoors and get medical care. Don't rub or massage the area, and don't warm it with a heating pad, stove or radiator, because numb skin burns easily.
Know the warning signs of hypothermia
The CDC lists the warning signs of hypothermia in adults as shivering, exhaustion, confusion, fumbling hands, memory loss, slurred speech and drowsiness. NIOSH lists the late signs as no shivering, blue skin, dilated pupils, slowed pulse and breathing, and loss of consciousness. A body temperature below 95°F (35°C) is a medical emergency. If a running partner becomes clumsy or confused, stop the run and get them somewhere warm. Remove any wet clothing and get medical help.
Be seen in the shorter daylight
Daylight saving time ends on Sunday, November 1, 2026, which pushes after-work runs into dusk or darkness. Both the Kansas and Drexel tips recommend reflective clothing. Add a light and choose well-lit routes. Our guide to keeping your workouts and sleep on track when daylight saving time ends covers the time change itself.
Respect ice
Drexel's running specialists note that snow is generally manageable, but ice is not. Slow down, stick to cleared routes, and be careful on shaded patches. Dr. Smith notes that some runners wear traction straps on snow and ice, and Drexel adds that trail-running shoes can help in snow. If the roads are glazed, run indoors.
Warm up, hydrate and change quickly
- Warm up: Drexel's specialists suggest starting slowly and extending your warm-up so your muscles can adjust. The Kansas tips also stress warming up and cooling down.
- Drink water: Drexel advises drinking water even though you may not feel thirsty in the cold. Our article on how much water you really need each day covers everyday fluid needs.
- Change into dry clothes: Once you're inside, change right away. The NWS and Drexel both recommend it, because damp layers chill you quickly after you stop.
Cold air, asthma and exercise-induced bronchoconstriction
In exercise-induced bronchoconstriction (EIB), the airways narrow during or after exercise. The American Thoracic Society notes that EIB occurs in a substantial proportion of people with asthma and can also occur in people without known asthma. The American College of Allergy, Asthma and Immunology (ACAAI) explains that cold air usually holds little moisture, and breathing dry air quickly dehydrates the airways and makes them narrow. The dryness, more than the temperature, is the likely trigger. ACAAI suggests covering your mouth and nose with a scarf or face mask in cold weather and warming up gently for about 15 minutes. If you cough, wheeze or feel tight in the chest on winter runs, talk to your doctor or an allergist rather than pushing through.
Heart conditions, Raynaud's and other health issues
ACSM's position stand says people with asthma and cardiovascular disease can exercise in the cold but should be monitored closely. If you have heart disease, high blood pressure, diabetes or circulation problems, ask your doctor about winter running and any limits you should follow. The same goes for Raynaud's phenomenon. The National Institute of Arthritis and Musculoskeletal and Skin Diseases (NIAMS) explains that in Raynaud's, blood vessels in the fingers and toes narrow, and cold is the most common trigger. The CDC also lists poor blood circulation as a frostbite risk factor.
When to move your run indoors
No single cutoff temperature suits everyone. ACSM's position is that exercise can be done safely in most cold-weather environments with the right precautions. Still, consider an indoor session in any of these situations:
- The wind chill is around −18°F (−27°C) or colder. That's ACSM's threshold for closer monitoring, and it's close to the NWS line for frostbite in 30 minutes.
- Roads or paths are icy.
- It's raining near freezing and you can't stay dry.
- You're new to winter running and the temperature is near 0°F (−18°C), where Drexel's specialists say to run inside.
A treadmill is the closest substitute. If you're thinking of buying one, our walking pad vs treadmill comparison explains why you need a full treadmill for running. Without one, our indoor workouts for bad air quality days work just as well on icy ones, and so do our home workouts that actually work.
FAQ
What should I wear running in 40-degree weather?
Under the 20-degree rule, a 40°F (4°C) run feels like about 60°F once you're warm. A long-sleeve wicking shirt with shorts or light tights, light gloves and a thin hat or headband is a good starting point. Add a light jacket or vest if it's windy or wet.
What temperature is too cold to run outside?
There's no universal limit. It depends on wind, ice, your health and your experience. For reference, the NWS chart shows frostbite on exposed skin in 30 minutes at a −19°F wind chill. ACSM recommends closer monitoring below a −18°F wind chill, and Drexel's running specialists suggest moving inside at about 0°F.
Are mittens or gloves better for winter running?
The NWS advises that mittens are better than gloves in extreme cold. Light gloves are usually enough in the 30s and 40s. Switch to mittens in the 20s and below, or whenever your fingers start going numb.
Is breathing cold air bad for your lungs when running?
It can be a problem if you're prone to exercise-induced bronchoconstriction. According to ACAAI, breathing cold, dry air quickly can dry out and narrow the airways. ACAAI suggests covering your mouth and nose with a scarf or face mask and warming up first. If you have symptoms, see a doctor.
This article is general information, not medical advice. The clothing table is a starting point based on the sources below, and no gear was tested for this article. If you have a heart or lung condition, Raynaud's or another health concern, talk to your doctor before running in the cold.
Sources
- The University of Kansas Health System: Keep a Healthy Running Pace This Winter (David Smith, MD).
- MU Health Care: Winter Running Tips (Aaron Gray, MD), November 13, 2017.
- Drexel University: Tips for Winter Running, from the Running Performance and Research Center, January 20, 2016.
- National Weather Service: Wind Chill Chart and the printable chart (PDF).
- National Weather Service: During Extremely Cold Weather.
- CDC: Preventing Frostbite.
- CDC: Preventing Hypothermia.
- NIOSH Fast Facts: Protecting Yourself from Cold Stress (PDF).
- Castellani et al., American College of Sports Medicine position stand: prevention of cold injuries during exercise, Medicine & Science in Sports & Exercise 2006.
- Parsons et al., An official American Thoracic Society clinical practice guideline: exercise-induced bronchoconstriction, American Journal of Respiratory and Critical Care Medicine 2013.
- ACAAI: Exercise-Induced Bronchoconstriction (EIB).
- NIAMS: Raynaud's Phenomenon.
