How Cold is Too Cold to Run Outside?

Two runners run down a path in the snow

It can be difficult to motivate yourself to get out for a run in the winter when the days are cold and short. As the warm air of your heated home caresses you and a new episode of your favorite show streams on Netflix, you may ask yourself, is this even safe? Will I catch a cold, or, even worse, end up with hypothermia or frostbite?

If so, you’re not alone. We sat down with a doctor, a coach, experienced winter runners and a Fleet Feet Outfitter in Boulder, Colorado to answer the question, “How cold is too cold to run outside?”

According to Dr. Blake Butler, a Functional Medicine doctor with Aligned Modern Health living in Castle Rock, Colorado, running in extreme cold (sub 0ºF) is dangerous. But with the right equipment and temperatures above 0ºF, cold weather running can have many benefits both physically and mentally.

Get the Gear that Will Keep You Safe and Comfortable

A man dresses in several layers before a run.

Whether it's 37 degrees and raining or pushing single digits, wearing the right gear is crucial for a successful run.

Keaton Reece, Customer Experience Manager at Fleet Feet’s Boulder Running Company, says every winter runner needs a few key pieces.

“Having a quality layering system is the key to success in winter running. You'll want to start with a base layer, made with material such as merino wool or a synthetic blend that will wick the sweat away from your skin to keep you dry. Depending how cold it is or how cold you get, you can add a midlayer, like a quarter zip or long sleeve that is also a wicking material,” says Reece, who runs in the mountains of Boulder all winter long. “Finally, you’ll want an outer shell which is designed to block wind and moisture while also trapping your body’s heat.”

Coach Mike Norman, co-owner and co-founder of Chicago Endurance Sports (CES), has been coaching runners since the mid 1990’s in the Chicago area. Norman says every runner is going to have slightly different needs and preferences, so there is no one perfect outfit for everyone. It will take some experimenting to determine what works best for you.

Once you have the right gear, running in the winter can be fun, challenging and rewarding. You may start to enjoy the crisp air against your face, the crunch of the frosted ground under your striding feet and the way the heat your body creates is held within your outer layer.

Learn more about how to dress in layers in the cold here

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Bring a Friend and Adjust Your Route

Two runners run in the snow.

If you are determined to get outside for a run in sub-freezing temperatures, inviting friends can help you stay motivated.

“Having a buddy to hold you accountable is huge,” says Norman. “That's probably one of the biggest things, is finding that community.”

He also suggests runners adjust their routes to be shorter loops rather than long out-and-backs or big loops on the coldest days. For example, if you typically do a six-mile loop from your house, try finding a three-mile loop so you don’t end up too far away in case you slip on ice or face another cold-related challenge.

Cynthia Wheeler, a runner of 20 years and Chicago local says winter is her favorite season to run.

“Running in Chicago in the winter is a little slice of magic. There are times when you have the whole city to yourself.” says Wheeler, who embraces the cold even in the single digits. “Start slow. Get the feel of the terrain you're on. It's tough to set personal bests on snow and ice. Don't try to do too much. Get out there and enjoy!”

Cold weather running challenges some runners more than others. Some people run hot and some run cold. It’s about experimenting with the proper gear and finding out what works best for you. Norman agrees. “We have a coach who I don't know if I've ever seen in long pants in the winter. This guy wears shorts pretty much all year round. Another one of our coaches walks around in four sweatshirts all the time,” Norman says. “Everybody is totally different.”

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Stay On Top of Hydration and Nutrition

On top of having the right gear, prior hydration and nutrition are crucial for staying safe even in the cold.

“It’s easy to forget about hydration in the winter because you might not feel as sweaty as in the summer,” says Nistler, who grew up in Minnesota and is well acquainted with long cold winters.

“Being dehydrated can actually contribute to cold weather injuries. Both frostbite and hypothermia are more likely to occur when there is an improper balance of water and electrolytes in the body.”

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A man and woman run through the snow.

Preparation is Key

“The body is very adaptable. It works towards something called homeostasis which is an internal balance,” Butler says. “Our bodies are internally intelligent as it relates to our response to the environment. I think we often don’t give it enough credit.”

Butler, who is an avid trail- and ultrarunner, says that preparation is key when facing extreme temperatures on the run.

“Typically hypothermia can take anywhere from less than 10 minutes to 12 hours depending on how extreme the weather conditions are and how well you are dressed and prepared for the environment,” he says. “A lot of it could have to do with your gear.”

Without the proper gear, your risk for hypothermia and mild frostbite are higher, especially when considering extreme conditions. It’s important to be aware of your body and the signs and symptoms of both conditions.

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Signs and Symptoms of Hypothermia

Even when running in cold weather, your body produces heat as the blood pumps through your veins. If you begin to shiver during exercise it can be an early sign of hypothermia, and you should head inside as soon as possible. If your symptoms transition to confusion, slurred speech or loss of fine motor skills, you should seek immediate medical attention, says Dr. Butler.

“If you experience these symptoms, I would recommend getting out of your cold clothes as soon as possible. Then I’d recommend putting on dry clothes and wrapping yourself in blankets to bring up that body temperature,” says Butler. “Once the shivering has dissipated you can take a warm shower or bath, some soup or warm fluids can also be helpful. Immediately jumping into a hot shower can often be painful and not provide the same value as warming up your body over time.”

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Know When to Say No

A man puts on a hat before a cold winter run.

If temperature or wind chill starts to dip around 0-degrees it’s time to consider staying indoors and opting for other options such as running on a treadmill or cross training.

Christina Nistler is an athletic trainer and owner of Superior Running Medicine based in Duluth, Minnesota. Nistler says, “For a general rule of thumb if it gets below 0-degrees Fahrenheit with any wind chill, exposed skin can freeze in 30 minutes. Of course skin covering like gloves, hats or buffs and well insulated gear will help. So if you are right around that zero degree mark, that doesn't mean you can’t go outside but you absolutely need the appropriate clothing.”

According to Butler, early signs of frostbite include prickly or numb sensations in the hands or any exposed skin, the change of skin color and the loss of joint coordination. As soon as any of these symptoms arise it is best practice to get inside and warm yourself up.

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