Wind Chill: What Is It And Why Can It Have Dangerous Consequences?

"Wind chill" is a term commonly used by meteorologists in the colder months, but do you know what it truly means and the dangers associated with it?

The wind chill is the effective temperature your body experiences based on the actual temperature with wind factored in. Forecasters often refer to wind chill as the "feels-like" temperature.

The wind strips away the thin layer of warm air above your skin. This layer of warm air helps to insulate your body when conditions are cold. When that layer is removed, your body perceives a temperature that is colder than the actual air temperature.

This effect does more than just make it feel colder: It quite literally causes your body to lose heat as if the measured temperature is colder.

(MAP: Current Wind Chills)

The wind chill also can be calculated as an equation with temperature and wind speed.

(Don't worry, there won't be a test.)

Luckily, meteorologists have already done the math for you, so you can use this chart to determine your wind chill.

The violet-shaded areas represent the amount of time it takes to get frostbite on exposed skin at the corresponding wind chill values.

(Data: NOAA, NWS)

You can determine your wind chill temperature using the chart above. Find the value closest to the outside air temperature, then the value closest to the current wind speed. The “wind chill” is the value where the imaginary lines drawn from the air temperature and the wind intersect.

The violet-shaded areas in the wind chill chart represent the amount of time it takes to get frostbite on exposed skin at the corresponding wind chill temperatures.

For example, with an air temperature of minus 20 degrees and a wind speed of 15 mph, the wind chill is 45 degrees below zero — and frostbite can occur in 10 minutes or less.

You can also approximate the wind chill even if the temperature isn't on the chart. If the temperature is minus 13 degrees and the wind speed is 15 mph, the wind chill will be somewhere between minus 32 and minus 39. So you can call that a minus 35 wind chill.

The Dangers Behind Wind Chill

Frostbite

As alluded to before, the primary risk of wind chill is frostbite on exposed skin.

Frostbite occurs when body tissue freezes, and it can be especially common in your fingers, toes, ear lobes or the tip of your nose. To protect vital organs, your body cuts circulation to your extremities, which eventually freeze.

And just because it may not be on the chart, you can still get frostbite at wind chills warmer than that roughly minus 16 degree mark. Frostbite just happens faster as the wind chill drops.

To avoid frostbite, the best thing to do is stay inside when it's bitterly cold.

If you have to be outside, you should cover every part of your body, including your ears, nose, toes and fingers. You also want to keep your skin dry and stay out of the wind when possible.

Make sure none of your clothing restricts blood flow, and try to keep moving to help with blood circulation.

Be sure to stay hydrated by drinking plenty of fluids. Hydration increases your blood's volume, which helps prevent frostbite by improving circulation.

It is also important to keep yourself, especially your feet, as dry as possible to avoid frostbite on your toes.

According to the NWS, there are four degrees of frostbite:

First degree: The skin's surface is frozen, known as frostnip.

Second degree: The skin may freeze and harden; blisters form in a day or two.

Third degree: Muscles, tendons, nerves and blood vessels freeze.

Fourth degree: Pain lasts for more than a few hours and skin may turn dark blue or black; gangrene is a real threat and will require amputation of extremities if it occurs.

Hypothermia

In addition to frostbite and damage to your extremities, extreme wind chills can also pose dangerous risks to your whole body. The colder the wind chill, the higher the risk for developing hypothermia.

Hypothermia occurs when your core body temperature, normally around 98.6 degrees, drops below 95 degrees.

The National Weather Service offers these tips for dealing with extreme cold:

Dress in layers

Cover exposed skin when going outside in the cold

Avoid breezes and drafts indoors

Eat nutritious food and wear warm clothes to ward off winter chill

Avoid consuming caffeine and alcohol

Wear a warm hat in the winter

Eat hot foods and drink warm drinks several times during the day

If you live alone, ask a family member or neighbor to check on you daily

Prepare a winter car survival kit when traveling

If your body temperature is 96 degrees or less, you feel cold and sluggish or are having trouble thinking clearly, the NWS says to see your doctor immediately or go to the nearest emergency room.

Hayden Marshall is a meteorologist intern and First-Year-Master’s Student at the Georgia Institute of Technology. He has been following weather content over the past three years as a Storm Spotter and weather enthusiast. He can be found on Instagram and Linkedin.