A large portion of the U.S.—including the Midwest and the East Coast as far south as Florida—is experiencing unusually frigid temperatures. And for many, the deep freeze that started the last week in December is predicted to continue. 

These lingering low temperatures can be hazardous to your health.

"People often underestimate the risk," says Randy Wexler, M.D., M.P.H., associate professor and vice chair of clinical services at the Ohio State University in Columbus. "They think they can be outside longer than they actually can be and dress for what they are used to."

The two greatest concerns are frostbite, which is when body tissue freezes—most often in the extremities—and hypothermia, when your body temperature falls below 95° F (the most common cold-weather-related cause of death).  

Here, from the experts, are the steps that can keep you safe when winter weather poses a threat and what to do if you suspect you have frostbite or hypothermia. 

More on Dealing with the Cold

During an especially cold period like this, it's important to check your local forecast before heading outside (sure, it sounds obvious, but plenty of people forget).

Be aware that there's no one low temperature at which the weather becomes dangerous. What's important to pay attention to is the wind chill temperature—a combination of actual temperature and wind speed—which tells you what it actually feels like outside, according to the National Oceanic and Atmospheric Administration (NOAA).

Be on the lookout for wind chill advisories (issued by the National Weather Service when wind chill temperatures are potentially dangerous) and wind chill warnings (issued when wind chill temperatures are life-threatening). The NWS wind chill chart and calculator can also help you determine how quickly frostbite may occur in different temperature and wind conditions. 

 

Protect Your Core

Keeping your core—the torso area—warm reduces the likelihood of hypothermia. And, notes Wexler, "a warm core will push warm blood out to the extremities."

The optimal clothing choices depend in part on how physically active you'll be when outside, and for how long you'll be exposed to the weather. Consider the following:

A jacket filled with down is an excellent way to maintain warmth if you're outside and relatively inactive, says Ken Zafren, M.D., a professor in the department of emergency medicine at Stanford University Medical Center in California, who served as the emergency programs medical director for the state of Alaska for 16 years.

Layers can also be quite effective, especially if you will be physically active when you’re outside. 

“It is much easier to make small adjustments to your clothing if you have layers you can add or remove," says Theodore Shybut, M.D., assistant professor of orthopedic surgery at Baylor College of Medicine in Houston. "Having multiple layers allows you to adjust your protective clothing if conditions change—the sun comes out or a storm blows in, or your exertion level changes and you heat up or cool off."

The first couple of layers should be moisture-wicking to prevent sweat from accumulating and lowering your body temperature. Synthetics such as polyester, polyethylene, microfiber, and polypropylene, and natural substances such as merino wool are all good choices, according to our experts.

They all agree that cotton is a poor option for extreme cold, especially if you sweat or get wet.

"Cotton is problematic because it absorbs huge amounts of water, many times its weight," Shybut says. Wet cotton also dries more slowly than wool or synthetics, cooling your body when you need to retain heat.

A fleece pullover or wool sweater can serve as an insulation layer, if needed, topped by a wind-resistant outer layer.

"Blocking wind will help prevent wintry gusts from pulling heat away from your body and clothing," Shybut says. Some jackets also wick moisture away or have side or armpit zippers that you can open and close as needed.

Keep those layers loose, advises Sharon Brangman, M.D., chief of geriatrics at SUNY Upstate Medical University in Syracuse, N.Y. Tight clothing can reduce circulation, she says.  

In addition, tuck a charged cell phone into your pocket to have in the event of an emergency.  

Safeguard Your Extremities

When temperatures are low and the wind is high, it's important to cover your extremities—the earlobes, tip of the nose, fingers, and toes—which are at highest risk for frostbite. That means a wool or synthetic hat that protects the ears, warm boots, and a face mask or scarf to shield the face.

For your hands, opt for mittens rather than gloves, advises Gordon Giesbrecht, Ph.D., physiologist and director of the Laboratory for Exercise and Environmental Medicine at the University of Manitoba in Canada. "This keeps your fingers together and warmer longer," he notes.

And while doubling up on socks can be a benefit when it's frigid, don't do this if it makes your boots feel tight. "This squeezes your feet and diminishes blood circulation—and blood delivers heat to the tissues," Giesbrecht adds.  

Make sure children, in particular, keep their hats firmly on their heads, says Stanford University Medical Center's Zafren. Frostbite on the ears is probably the most common cold-weather-related injury in youngsters, he says: “They don’t like to wear hats.”

Take Extra Care With the Most Vulnerable

"The elderly and young children are particularly vulnerable to the cold—the elderly because their thermal regulatory mechanisms are not as functional as when they were younger," says Wexler at Ohio State University.

Babies may have a harder time maintaining a normal body temperature, in part, he says, because their heads are disproportionately large and they tend to lose heat through their heads. So, be extra careful to keep babies and the elderly dressed properly and to limit their time in the cold.

People with chronic conditions such as diabetes and heart failure may also have difficulty regulating body temperature properly and need to pay close attention in cold weather. Those with diabetes, for instance, says Wexler, may have nerve damage in their extremities, which can reduce their ability to sense a significant temperature change.  

Avoid Alcohol and Smoking

Alcohol itself can slightly increase frostbite risk, says Zafren, but more importantly, being intoxicated may affect your ability to know when to seek appropriate shelter.

Smoking, which constricts blood vessels, does boost the likelihood of frostbite. So if you smoke, try to skip cigarettes if you’re going to be exposed to very cold temperatures.

Be Aware of Danger Signs

If your extremities are chilly but not numb and you can't get inside right away, you can try a few tactics to warm them up, such as tucking your hands into your armpits or swinging your arms around.

But if you experience a loss of feeling in one or more of your extremities or if they have a white, waxy, or pale look, chances are it's frostbite.

"If it's super cold, you can get frostbite in less than a minute," says Zafren."That’s the time to get indoors and put on more clothes."

If this doesn't work, call your doctor; you may need expert help.

The signs of hypothermia are not always easy to recognize. It can start with uncontrollable shivering and then progress to disorientation, slurred speech, drowsiness, and exhaustion. If you experience these symptoms (or are with someone else who is) get inside and summon medical help immediately: "Rewarming" isn't something you can do yourself. Here's more on frostbite and hypothermia from the Centers for Disease Control and Prevention.