Windy days lead to windchill dangers

The NWS Windchill Temperature index calculates wind speed at an average height of 5 feet, the typical height of an adult human face, incorporates heat loss from the body to its surroundings during cold and breezy/windy days, lowers the calm wind threshold to 3 mph, uses a consistent standard for skin tissue resistance, and assumes no impact from the sun, i.e., a clear night sky.

Chart courtesy of National Weather Service

 

The sun is out and temperatures are above freezing – no worries about sending kids outside to play in the snow, right? It all depends on the wind, and associated wind chill. 

According to the National Weather Service, wind chill temperature is described as how cold people and animals feel when outside. 

Wind chill is based on the rate of heat loss from exposed skin caused by wind and cold. As the wind increases, it draws heat from the body, driving down skin temperature and eventually the internal body temperature. Therefore, the wind makes it feel much colder than the temperature on the thermometer, something most in Central Montana are well aware of.

For example, if the temperature is 0°F and the wind is blowing at 15 mph, the wind chill is -19°F. The air temperature has to be below freezing for frostbite to develop on exposed skin. Wind chill can not bring the temperature to below freezing for humans and animals when the thermometer says it is above freezing, so you will not get frostbite; however, you might get hypothermia from exposure to cold. In summary, you can only get frostbite if the actual air temperature, not the wind chill temperature, near your skin is below freezing.

 

Windchill only applies to living things

The only effect wind chill has on inanimate objects, such as car radiators and water pipes, is to shorten the amount of time for the object to cool. The inanimate object will not cool below the actual air temperature. For example, if the temperature outside is -5°F and the wind chill temperature is -31°F, your car’s radiator will not drop lower than -5°F.

 

Avoid windchill issues with proper preparation

The best way to avoid hypothermia and frostbite is to stay warm and dry indoors and outdoors. When you must go outside, wear several layers of loose-fitting, lightweight, warm clothing. Trapped air between the layers will insulate you. 

• Remove layers to avoid sweating and chill.

• Outer garments should be tightly woven, water repellent and hooded.

• Wear a hat because much of your body heat can be lost from your head.

• Cover your mouth to protect your lungs from extreme cold.

• Mittens, snug at the wrist, are better than gloves.

• Try to stay dry and out of the wind.

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