You might want to pick out an extra layer or seven over the next few days. A deep freeze, which could be the coldest in a generation, is due to hit 55 million Americans. The air will be so cold that the National Weather Service in Des Moines, Iowa, has warned that, if people go outside, they should “avoid taking deep breaths, and minimize talking.” It's predicted that Wednesday could be the coldest day ever recorded in Chicago—its all-time coldest temperature record currently stands at 27 degrees below zero, according to USA Today. Wind chills as low as 55 below zero are likely in the city, and some areas in the northern Plains could see wind chills of 64 degrees below zero. The cold won't be quite as bad on the East Coast. Lows Wednesday night will reach 6 degrees in New York, 7 degrees in Philadelphia, and 9 degrees in Washington DC. AccuWeather meteorologist Mike Doll said: “I cannot stress how dangerously cold it will be... An entire generation has gone by without experiencing this type of cold.”