General weather information only, from the National Weather Service.
Wind chill describes what the air temperature feels like to human skin.
It comes from the combination of cold temperatures and wind blowing on exposed skin.
The temperature it feels like outside, from the air temperature and the wind speed together, is called the “wind chill.”
The colder the air temperature and the higher the wind speed, the colder it feels on your skin.
Even if the temperature stays the same, a higher wind speed makes it feel colder.
As wind blows across our bodies, it takes the heat we naturally emit and blows it away.
The faster the wind, the faster our body heat is taken away, and the colder it feels.
It works like blowing on a hot bowl of soup to cool it down.
The National Weather Service wind chill chart shows the wind chill for different air temperatures and wind speeds.
The colors on the chart are a frostbite indicator.
They show the combinations of temperature, wind speed, and exposure time that will produce frostbite on humans.
Each shaded area shows how long a person can be exposed before frostbite develops.
Worked example
Air temperature: 0°F
Wind speed: 15 mph
Wind chill temperature: -19°F
Under those conditions, exposed skin can freeze in 30 minutes.
The National Weather Service also has a wind chill calculator on its winter weather page.
The National Weather Service Wind Chill Temperature index uses advances in science, technology, and computer modeling.
It gives an accurate, understandable, and useful formula for the dangers from winter winds and freezing temperatures.
In early summer 2001, human trials were run at the Defence and Civil Institute of Environmental Medicine in Toronto, Canada.
Twelve volunteers took part — six men and six women.
They were placed in a chilled wind tunnel with thermal sensors on their faces, on the cheeks, forehead, nose, and chin.
They walked 3 mph on a treadmill.
Each volunteer took part in four 90-minute trials, at different wind speeds and temperatures.
The results improved the formula and set the frostbite threshold values.
The new wind chill index is now used in Canada and the United States.
The Wind Chill Temperature index:
Source: National Weather Service, Weather Forecast Office Amarillo, “Wind Chill,” weather.gov.
General weather information only, from the National Weather Service.