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Prepared by Associate Extension Professor Barbara Murphy

It is winter in Maine and it’s cold outside, but how cold is cold? A thermometer reading tells us only how cold the outside air is. However when the wind is blowing, a much better indicator of how cold you will feel is the wind-chill temperature.

What is Wind Chill?

The wind chill temperature indicates how cold the winds make the exposed flesh of animals and humans feel. On a calm day, our bodies insulate us somewhat by warming up a thin layer of air close to our skin. As the wind blows it takes this protective layer away, exposing our skin to the outside temperature. It takes energy for our bodies to warm up a new layer, and as each layer keeps getting blown away, our skin temperature—and possibly our internal body temperature as well—decreases, and we feel colder.

The wind chill temperature is a good way to gauge the potential for frostbite, which occurs when skin and underlying tissue become frozen, as well as hypothermia, which occurs when body temperature drops below 95°F. Wind chill temperatures apply only to humans and animals. If the temperature is 35°F and the wind chill is 10°F, objects such as cars or water pipes will only cool to 35°F. Wind chill will, however, shorten the amount of time needed for objects to cool.

Source: Office of Climate, Water, and Weather Services, “NWS Windchill Chart,” National Oceanic and Atmospheric Administration's National Weather Service, http://www.weather.gov/om/windchill.

Beating the Chill

The effects of wind chill can be reduced by wearing clothing with high insulating properties, such as wool, fleece, and synthetic thermal materials. Such materials trap air, creating a thicker layer around the body that holds heat. Dressing in layers also traps insulating air around your body.

Wear an outer layer that is wind- and water-resistant and hooded. Most wet clothing, including footwear, looses its insulating value, so try to stay dry. Wear a hat to avoid losing body heat from your head, and wear mittens rather than gloves. Cover all exposed skin, and keep your mouth covered to shield your lungs from severe cold.

Seeking shelter from the wind can help reduce the wind chill effect. Exercise is another way to beat the chill; it revs up your metabolism and generates heat. Remember that older adults and children have less muscle mass so they generate less body heat. Adjust their exposure time accordingly.

Finally, avoid going outside if the forecast is predicting extreme wind chill. And keep these rough guidelines in mind:

• Frostbite can occur in 30 minutes at a wind chill temperature of -25°F.

• Frostbite can occur in 10 minutes at a wind chill temperature of -35°F.

• Frostbite can occur in 5 minutes at a wind chill temperature of -55°F.

References

Office of Climate, Water, and Weather Services. “Windchill Terms and Definitions.” National Oceanic and Atmospheric Administration's National Weather Service. http://www.weather.gov/os/windchill/windchillglossary.shtml.

Office of Climate, Water, and Weather Services. “New! Wind Chill Temperature Index” (brochure). National Oceanic and Atmospheric Administration's National Weather Service. http://www.weather.gov/om/windchill/images/wind-chill-brochure.pdf.

The Meteorological Service of Canada. “Environment Canada’s Wind Chill Program.” Environment Canada. http://www.msc-smc.ec.gc.ca/education/windchill/index_e.cfm.

Disaster Resources. “Wind Chill.” University of Illinois Extension. http://web.extension.uiuc.edu/disaster/winter/ws_chill.html.

© 2008