Wind chills are wreaking havoc in the northern and central parts of the United States while it has snowed heavily from the Eastern Plain to the Great Lakes of the country due to invasion of arctic cold air. The National Weather Service said in an advisory posted at its website Sunday that the northern and central parts of the U.S. will expect the coldest temperatures in about two decades this week because of the polar cold front, with some 140 million people to be impacted. Combined with gusty winds, the temperatures will result in "life-threatening wind chill values as low as 60 degrees below zero (Fahrenheit or minus 51 degrees Celsius)" in some areas. The frigidly cold weather has caused travel nightmares for people who are heading for home from holidays, said local media reports. In Chicago, the U.S. state of Illinois, a new round of heavy snow started to fall from Saturday. The city's O'Hare International Airport was forced to cancel 1,200 flights as the snowing weather continued Sunday, coupled with gusty winds. As the city was bracing for the winter storm Sunday, local officials say they are expecting 25 centimeters to 30 centimeters of snow to accumulate in the Chicago area by Sunday evening. John f. Kennedy International Airport in the East Coast's New York City, which had heavy snowfall from Thursday night to early Friday, also announced to temporarily suspend operations for domestic and international flights due to icing conditions early Sunday morning. It reopened for arriving and departing flights later in the day, but with residual delays. More than 3,000 flights were canceled Sunday at the country's airports nationwide because of the bone chilling cold and icy weather, according to flight-tracking website flightaware.com. Schools and governments in some cities will remain closed because of the deep freeze which will also affect certain southern U.S. states, said local news reports. "The good news is that it will be a quick event, and moderating temperatures are expected to return by Wednesday," said weather forecasters.