In pictures: US and Canada blanketed by frigid air

Local residents help clear snow at Highmark Stadium in Buffalo ahead of the AFC Wild Card playoff game on Monday

More than 142 million people across the US are under a wind chill alert on Monday, as frigid Arctic air hangs over much of the country.

The National Weather Service (NWS) said the heartland of the US will likely experience record-breaking cold.

Temperatures in Montana are forecast to plunge below -50F (-45C).

The deep freeze may affect voter turnout in Iowa, as the state gears up to choose its Republican candidate for the 2024 election.

In its advisory on Monday, the NWS warned of "brutally cold temperatures" that will persist until Wednesday.

The cold is thanks to an Arctic air mass that has travelled southeast into the US from western Canada - where it set record-low temperatures.

A frozen Edmonton, Alberta on 13 January

In Edmonton, Alberta, temperatures reached a bone-chilling record-low of -49.5F (-45.3C) on Saturday. The cold has strained Alberta's energy grid, and at one point the province issued an emergency alert asking people to turn off unnecessary appliances at the risk of widespread power outages.

As of Monday, all of Alberta remains under an extreme cold warning, with Environment Canada urging people to bundle up, as "frostbite can develop within minutes on exposed skin, especially with wind chill".

At least six million Canadians are under an extreme cold warning, mainly in Alberta, Saskatchewan and parts of British Columbia.

A tree covered in ice as a result of steam exhaust from a chemical plant in Ames, Iowa

With much of that Arctic air mass now also hanging over the American heartland, political analysts are weighing whether the cold will hamper voter turn out in Iowa, where the state's caucuses are being held on Monday.

Iowa has been grappling with extreme cold and heavy snow for much of the weekend, forcing the cancellation of some campaign events,

On Monday, temperatures in some parts of the state are expected to dip as low as -40F (-40C) with the wind chill.

Iowans try to stay warm in the face of bitter cold temeperatures

A volunteer plunges campaign signs for Republican Presidential Candidate Ron DeSantis into deep snow in Cedar Rapids, Iowa

The winter weather has even disrupted the National Football League's playoff schedule.

A snowstorm in New York forced the Sunday wild-card round game between the Buffalo Bills and Pittsburgh Steelers to be rescheduled to Monday instead. The Bills asked for hired help to shovel snow from the stadium head of the game and plenty of people obliged.

June Jarnot shovels snow after the Buffalo Bills appeal for help ahead on the game on Monday

The AFC Wild Card game between the Kansas City Chiefs and the Miami Dolphins, however, went ahead as scheduled on Saturday, despite temperatures on the field reaching -28F (-33C) with the wind chill.

Arrowhead Stadium was frozen ahead of the AFC Wild Card playoff game on Saturday

Elsewhere in the country, a mix of snow, sleet and freezing rain is expected across the Lower Mississippi Valley and the Tennessee Valley, supported in part by the frigid cold temperatures.

Out west, a winter storm watch has been issued for parts of Washington State, as well as Portland, Oregon, where ongoing power outages have forced more than 100,000 households and businesses to weather the cold without any heat or electricity for the last three days.

Cold temperatures in Texas have also knocked power out for nearly 25,000 others. With more cold weather in the forecast, officials urged residents on Monday to conserve electricity use to ease the load on the state's power grid.

A Dallas police officer directs traffic on Monday ahead of a basketball game between the Dallas Mavericks and the New Orleans Pelicans

While the NWS anticipates there will be some relief from the cold by Wednesday, it will be short-lived.

Another surge of Arctic air is expected to travel southward from Canada later this week, which could lead to more frigid temperatures across the Midwest and deep South by Friday.