Ice floats on New York's East River as cold front sweeps the US

New York's East River is covered in ice as freezing temperatures grip swathes of the country in a monster storm that has killed at least 30 people.

A frigid, life-threatening Arctic air mass could delay recovery as municipalities from New Mexico to Maine tried to dig out following the storm, which dropped a vicious cocktail of heavy snow and wind, along with freezing rain and sleet.

Forecasters warned that much of the northern half of the country will see temperatures that are "continuously below freezing through February 1," the National Weather Service said. It added that "record low temperatures" hit southern states, which are unaccustomed to intense winter weather.