The National Weather Service is forecasting extremely low temperatures in many parts of the US overnight:
- -34 C in Minneapolis, Minnesota
- -24 C in Chicago, Illinois and Indianapolis, Indiana
- -31 C in Fargo, North Dakota
The lowest temperature reported in the lower 48 states on Sunday was -40 C in the towns of Babbitt and Embarrass in Minnesota.
Air passengers in the US face another day of disruption due to the extreme cold weather.
More than 7,300 flights were delayed and 3,514 were cancelled on Sunday, according to the aviation tracking website Flightaware.com.
The website's live 'Misery Map' showed the highest numbers of cancellations and delays from Denver International Airport in Colorado and Chicago O'Hare International Airport in Illinois.
Pictures of New York City in the grip of the snow storm plaguing north-east America have emerged as the metropolis braces for a "polar vortex".
City leaders declared a state of emergency as a snow storm dubbed "Hercules" sweeps across the north east of America.
Storm Hercules dumped 21 inches of snow on Boxford, just north of Boston, by Thursday night, according to the National Weather Service.
Fans of the National Football League's Green Bay Packers risked frostbite in the US state of Wisconsin weather to watch a game amid the lowest temperatures in two decades.
Packers fans dressed in multiple layers of their team's green and gold uniforms were undaunted by a forecast for temperatures, with some bringing along barbecues and bottles of beer.
Officials at the stadium promised fans two free hot cocoa or coffee drinks during the game, sports network ESPN reported.
Icy air and gusting winds are expected to bring temperatures down as low as -50C in parts of the US with forecasters warning the Arctic grip could be life threatening.
The "polar vortex" - a rotating pool of cold, dense air - has brought the coldest weather in 20 years to the Mid-West.
ITV News' Lewis Vaughan-Jones reports from a nation bracing itself for the bitterest of weather:
Many parts of the US Midwest braced for a blast of Arctic air this weekend that could bring some of the coldest temperatures in two decades before advancing to the Northeast, where residents are still digging out from a deadly snowstorm.
The deep freeze will be felt in the northern US plains, including North and South Dakota, and through the Great Lakes region and Ohio Valley, according to the National Weather Service.
It will be some of the coldest weather to grip the region in two decades, with blizzard conditions expected in the Central Plains and Great Lakes regions, forecasters said.
Across the Atlantic, snow storms are threatening America with some of the coldest temperatures in two decades. Arctic air, heavy snow and high winds are expected to send the temperature plummeting to as low as 50 degrees below zero.
Ben Chapman reports:
At least 16 deaths have been blamed on a winter storm that dumped nearly 2ft of snow in parts of north-east America.
Light, fluffy snow meant an easier time digging out than it might have been and the storm caused just a few thousand power cuts. But the bone-chilling cold could mean a risk of frostbite for anyone who spends more than a few minutes outside.
Wind chills around New England were reported as low as minus 20 degrees Fahrenheit and forecasters warn it could be just as bad today.
Temperatures in the north east are expected to rise above freezing this weekend before the arrival of another blast of frigid air already affecting the Midwest.
People across the northeastern United States had to dig their way out of a heavy snowfall that grounded flights, closed schools and government offices, caused at least three deaths and left the region in the grip of dangerously low temperatures.
Boston was hard-hit by the first major winter storm of 2014, getting nearly 18 inches (45 cm) of snow, while some towns north of New England's largest city saw close to 2 feet (60 cm) of accumulation.
Major cities from Washington, D.C., to Portland, Maine, were slammed, with New York's Manhattan island getting 6 inches (15 cm) of snow and parts of the borough of Queens seeing more than 10 inches (26 cm) of fresh powder.