How Cold is Too Cold to Run: 15 Tips

Snow and frost can be motivating for dedicated runners. Winter is the perfect time of year to get out for a workout, but extremely cold weather brings real risks. Many runners notice:

• Burning lungs from breathing cold air

• Numb fingers, even with gloves

• Breath turning to visible clouds in the cold

It raises an important question: at what temperature should we stay inside?

The American College of Sports Medicine recommends avoiding outdoor training when air temperature drops below -18°F (-27°C), as tissue injury can occur within 30 minutes. For most amateur runners, sports medicine specialists recommend staying indoors when temperatures reach 0°F or below. However, the thermometer is not the only factor. Wind chill, humidity, and preparation are all critical in determining whether cold-weather running is safe.

Here are 15 practical tips for safe winter training. These recommendations are based on research by medical professionals and coaches focused on cold-weather performance.

Quick Reference: Winter Running Safety Guidelines

1. Know Your Temperature Threshold

Running in temperatures between 32°F and 20°F is generally safe for most runners. According to the Mayo Clinic:

• The risk of frostbite is less than 5% when the air temperature remains above 5°F

• Below 5°F, exposed skin can freeze in 30 minutes or less, depending on wind conditions

Extra caution is needed as temperatures drop below 20°F. Most experts recommend staying indoors when temperatures fall below 15°F or when the wind chill drops below 10°F.

2. Factor in Wind Chill, Not Temperature Alone

A 25°F day with 20 mph winds results in a heat loss equivalent to -4°F in calm conditions. According to NOAA, if the temperature is 0°F and there is no wind, exposed skin may take more than 30 minutes to freeze. Add 15 mph winds, and the wind chill drops to -19°F, reducing that time to a few minutes.

Check wind chill forecasts before heading out. The actual air temperature can differ significantly from the stated temperature.

3. Double Your Warmup Time

Cold muscles strain more easily than warm ones. Mayo Clinic advises doubling warm-up time in freezing conditions because your muscles take longer to acclimate. Start with aerobic movements before any static stretching to improve muscle flexibility.

Certified personal trainer Taylor Wilson recommends warming up indoors to activate and prepare your muscles. Dynamic stretches like leg swings or lunges reduce injury risk before you step into freezing temperatures.

4. Dress for 15 to 20 Degrees Warmer

A general rule is to dress for the weather 15 to 20 degrees warmer than the actual temperature. For example, if running in 30°F weather, dress as if it were 45 to 50°F. Feeling a slight chill at first is normal.

Within 5 to 10 minutes of running, most people feel warmer and may start sweating. This helps prevent overheating while still offering protection.

5. Avoid Cotton at All Costs

Wet fabric draws heat from the body much faster than air. Cotton absorbs sweat and stays damp, increasing heat loss. Mayo Clinic recommends synthetic materials, such as polypropylene, for the base layer to wick away sweat.

Once temperatures drop below 20°F, sports medicine specialist Dr. Eliza Pierko at Loyola Medicine recommends three layers for your upper body. Above that temperature, two solid layers usually provide adequate protection.

6. Layer Strategically for Easy Removal

The Mayo Clinic warns that dressing too warmly is a common mistake during cold-weather exercise. Your body generates considerable heat during a run, enough to make conditions feel much warmer than they are. But sweat evaporation then pulls heat away, leaving you chilled.

Layering works best:

• Start with a thin synthetic base layer

• Add an insulating middle layer

• Top with a wind-resistant outer layer, you can remove or add based on comfort

Remove outer layers as soon as you start sweating, then reapply if needed.

7. Protect Your Extremities First

The Mayo Clinic Health System recommends wearing thin, wicking glove liners under heavier gloves or mittens lined with wool or fleece. Remove the outer pair when your hands get sweaty.

Wear thermal socks and consider running shoes one size larger than usual to accommodate thicker socks. A hat or headband helps prevent heat loss from your head, which remains critical because blood flow to your scalp continues even as your body restricts circulation to your fingers and toes.

8. Cover Your Face in Extreme Cold

If temperatures drop substantially, a scarf or ski mask is necessary to cover your face. According to New York Road Runners, frostbite occurs when circulation becomes restricted in extremities, including fingers, toes, ears, and nose. Symptoms include numbness and skin turning white or blue.

A face covering helps warm the air before you inhale, which can reduce discomfort and protect your lungs.

9. Breathe Through Your Nose

Mayo Clinic pulmonologist Dr. Aryan Shiari explains that extreme cold air can cause spasms in the bronchial passages, making breathing more difficult. Breathing in through your nose and exhaling through your mouth is more effective because your nose humidifies and warms the air more efficiently than your mouth.

A scarf or ski mask over your nose and mouth helps retain heat and moisture, making breathing more comfortable.

10. Manage Pre-Existing Respiratory Conditions

The American Lung Association notes that cold, dry air often irritates airways, even in healthy lungs. For those with asthma or chronic obstructive pulmonary disease, being active outdoors in winter poses additional concerns. Dr. Albert Rizzo, senior medical advisor to the American Lung Association, explains that airways already inflamed react to cold air with further inflammation, muscle constriction, and increased mucus production.

As many as 90% of people with asthma also have exercise-induced bronchoconstriction. If this applies to you, the American Lung Association advises using a quick-relief inhaler 20 to 30 minutes before venturing outside.

11. Stay Hydrated Despite Reduced Thirst

Hydration is essential during cold-weather running. Thirst perception drops by nearly 40% in cold conditions compared to warmer weather, so it’s easier to become dehydrated without noticing.

Dry winter air also increases respiratory water loss because each exhaled breath releases more moisture than in warmer conditions. Cold-induced diuresis, meaning increased urine production in cold weather, further depletes water levels.

12. Follow Specific Hydration Guidelines

The American College of Sports Medicine recommends:

• Drink 5 to 7 milliliters of a hydration or sports drink per kilogram of body weight (about 1 ounce per 10 pounds) about 4 hours before exercise.

• During your run, drink when thirsty, but no more than 1 cup (8 ounces) every 20 minutes.

Room-temperature water works better than ice-cold water for winter runs. Keep a small bottle within your layers to maintain warmth.

13. Watch for Warning Signs

New York Road Runners explains that hypothermia occurs when body temperature falls below 95°F, with symptoms including confusion and uncontrollable shivering. The Road Runners Club of America notes that shivering is a vital early sign that your body is losing heat faster than it can produce it.

Hypothermia can occur even at temperatures above 40°F if you become chilled from rain, sweat, or exposure to cold water. Frostbite and hypothermia account for 20% of all injuries among Nordic skiers, a group that trains extensively in freezing conditions.

14. Choose Safe Routes and Tell Someone

The National Federation of State High School Associations warns that training alone, in remote locations, and at unusual hours increases the potential duration of cold exposure if injury occurs. Heat generation stops when you stop moving, but heat loss continues, leading to rapid cooling.

Tell a friend or family member your running route and expected return time. They can alert authorities if you become injured and do not return on schedule. Road Runners Club of America-certified coach Jay Silva adds that black ice typically appears during the winter months. Adjust your stride to shorter, quicker steps to maintain balance and avoid slipping.

15. Know When Indoor Training Makes More Sense

Some conditions warrant staying inside entirely. If you have asthma, heart problems, Raynaud’s disease, lung disease, or lupus, consult with your primary care team about appropriate precautions before cold-weather training.

The American College of Sports Medicine maintains that exercise can be performed safely in most cold conditions when proper risk management is employed. But "most" does not mean “all.” When the wind chill drops below -18°F, the organization recommends choosing indoor alternatives.

The Reward of Cold-Weather Training

Sue Karpinski, an employee well-being specialist at Mayo Clinic Health System, states that outdoor winter exercise can be beneficial when done correctly. Research suggests that exercising in cold weather may help convert white fat into beige or brown fat, which burns calories and generates heat.

Studies suggest that many marathon runners perform best when temperatures are around 44°F to 45°F, as cooler weather can reduce stress on the body and improve efficiency.

With careful layering, hydration, and planning, winter running can be safe and productive. Many runners enjoy cold air, quiet streets, and fewer crowds during the winter months.

Preparation means knowing personal limits. As temperatures drop and wind increases, assess conditions before heading out. Listen to your body for signs that it’s time to stop.