Extremely cold air comes every winter to at least part of the United States and affects millions of people. Arctic air and brisk winds can lead to dangerously cold wind chill values, resulting in frostbite and hypothermia. About 63% of weather-related deaths in the U.S. result from exposure to excessive cold and/or hypothermia. Extreme cold can also lead to significant damage to buildings and infrastructure, resulting in $500-million in average annual insured losses. This lesson describes the potential impacts of cold wind chill values and extremely cold temperatures, and explores ways forecasters can communicate the impacts of these weather events along with mitigation strategies.