Nine people have died in the US as the country grapples with a winter storm that has seen temperatures plunge as low as -45C (-49F).

More than 200 million people – around 60% of the US population – are under some form of weather warning or advisory, with the brutal cold expected to continue through the Christmas weekend.

State of emergency in New York – US bomb cyclone live updates

The nine weather-related deaths so far:

• Two deaths as a result of car crashes in Kentucky
• A homeless person died in the city of Louisville
• Three crashes in Oklahoma killed three people – two of the crashes happened as winds blew the drifting snow, while details of the third crash were not yet available
• The driver of a car in Missouri died after losing control on an icy road, going down an embankment, over a cement wall and landing upside down in a creek
• One person died in Wisconsin after a pick-up truck drove into the back of another vehicle before leaving the road and hitting a tractor-trailer unit parked on the hard shoulder
• A man was found dead on Friday morning in Memphis and, although there are no details, authorities have said it appears the death is weather-related

The Kansas Highway Patrol also said three people were killed in separate vehicle collisions on Wednesday, as the storm began, with drivers losing control of their vehicles on icy roads.

Temperatures across inland states have plunged: -45.6C (-50F) in Montana, and Des Moines in Iowa feeling like -38C (-37F), making it possible to suffer frostbite in less than five minutes, according to the National Weather Service.

Heavy snow and blizzard conditions are continuing around parts of the Great Lakes area – which covers lakes Superior, Michigan, Huron, Erie, and Ontario – with as much as 4ft of snow expected on the eastern side of Lake Ontario and Lake Erie.

Gusty winds have snapped trees and taken down power lines, with at least 1.4 million homes and businesses without electricity on Friday morning.

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Biden: ‘This is serious stuff’

According to the website poweroutage.us, Maine, Pennsylvania, Virginia, and North Carolina were the worst-affected, followed by Tennessee, New York, Maryland, and Connecticut.

More than 5,000 flights into, within and out of the US were cancelled on Friday, and there is a rush to open enough emergency shelters for those who are homeless or have no power at home.

There are also urgent efforts being made to get firewood to some Native American tribes who live remotely, such as members of the Rosebud Sioux Tribe and the Oglala Sioux Tribe in South Dakota.

Tribal president Frank Star Comes Out described the efforts as “one heck of a fight so far”.

US President Joe Biden said: “This is not like a snow day when you were a kid – this is serious stuff.”

Canada is also experiencing a bad storm, which has seen hundreds of flights delayed or cancelled and hundreds of thousands of properties without power.

Ontario Provincial Police Sergeant Kerry Schmidt said police had received reports of up to 100 vehicles involved in multiple collisions that have closed off a major highway near London, Ontario.