Arctic freeze continues to blast huge swaths of the US with sub-zero temperature

Brutally cold temperatures and dangerous wind chills stayed put across much of the U.S. Monday, promising the coldest temperatures ever for Iowass presidential nominating contest, holding up travelers, and testing the mettle of NFL fans in Buffalo for a playoff game that was delayed a day by wind-whipped snow.
About 150 million Americans were under a windchill warning or advisory for dangerous cold and wind, said Zack Taylor, a meteorologist with the National Weather Service in College Park, Maryland, as an Arctic air mass spilled south and eastward across the U.S.
Sunday morning saw temperatures as low as minus 6.7 degrees Celsius to minus minus 40 degrees Celcius in northern and northeast Montana.