A new blast of lake-effect snow began pounding Buffalo on Thursday, piling more misery on a city already buried by an epic, deadly snowfall that could leave some areas with nearly two-and-a-half metres of snow on the ground when it's all done.

But the meteorological "kick me" sign on the city hasn't fallen off just yet. Forecasters say a rapid weekend warmup, with temperatures as high as 15 C and heavy rain, could turn all that snow into floods.

With more snow forecast, New York Gov. Andrew Cuomo on Wednesday afternoon urged residents of upstate New York to stay off the roads, warning that the crisis will likely get “worse before it gets better.”

"Mother Nature is showing us who’s boss again,” Cuomo said in a news conference. 

The storm dumped massive amounts of snow on parts of upstate New York, trapping residents in their homes and stranding motorists on roadways, as the temperature in all 50 states fell to freezing or below.

Cuomo said the amount of snow, the rate at which the snow is falling and the weight of the snow have all conspired to make this an “extraordinarily difficult situation.”

Stranded vehicles have worsened the situation, as roads cannot be accessed or plowed until the cars are removed, Cuomo said.

"When we say stay home, really stay home. Going out on the roads is dangerous. It's unnecessary. You're not going got get anywhere," he said. "You will get stuck and then you will further complicate the situation."

Even hardened Buffalo residents were caught off-guard Tuesday as more than 150 centimetres fell in parts of the city by Wednesday morning. Authorities said snow totals by the afternoon could top 180 centimetres in the hardest-hit areas south of Buffalo, with another potential 30 to 60 centimetres expected by Thursday.

“It’s going to get, in some ways worse, before it gets better," Cuomo said.

Cold weather enveloped the entire U.S. Tuesday, leading to record-low temperatures more familiar to January than November. Racing winds and icy roads caused accidents, school closings and delays in municipal operations from the Midwest to the South even where snowfall was low or mercifully absent.

Even Hawaii was bitten by temperatures at the freezing point or below, the National Weather Service said.

Hawaii's Mauna Kea, a dormant volcano, had low temperatures of –1 C, said NWS spokeswoman Susan Buchanan.

Deaths in 3 states

The storm was blamed for at least seven deaths in New York, New Hampshire and Michigan.

Erie County officials said a 46-year-old man was discovered early Wednesday in his car, which was in a ditch and buried in snow in the town of Alden, 38 kilometres east of Buffalo. It was unclear how he died.

On Tuesday, county officials said four people had died, including three from heart attacks and one who was pinned beneath a car he was trying to free from the snow. Two of the heart attack victims were believed to be stricken while shovelling snow.

"We have tried to get out of our house, and we are lucky to be able to shovel so we can open the door," said Linda Oakley of Buffalo. "We're just thinking that in case of an emergency we can at least get out the door. We can't go any further."

The snowstorm forced motorists in 150 vehicles, including a women's basketball team, to ride out the onslaught in their vehicles. They waited for hours to be freed, with some waiting more than a day. Cuomo deployed 150 members of the National Guard to help clear snow-clogged roads and remove abandoned vehicles.

By early Wednesday, a Thruway official said most but not all passenger vehicles had been cleared.

'It seemed like a nightmare'

Members of the Niagara University's women's basketball team were among the lucky ones. Stranded since 1 a.m. ET Tuesday, team members tweeted photos of a plow starting to clear the road.

Local weather stories from CBC News:

"It seemed like a nightmare. It just didn't feel like it was going to end," Bryce Foreback, 23, of Shicora, Pa., told The Associated Press by cellphone 20 hours into his wait for help. "I haven't slept in like 30 hours and I'm just waiting to get out of here."

Foreback had become stuck in a long line of cars near the Lackawanna toll booths just south of Buffalo about 10:30 Monday night.

Wintry Weather New York

Omer Odovsc walks in front of his tractor-trailer that got stuck in Boston, N.Y. (Henry Scull Jr./The Buffalo News/Associated Press)

Winds force highway closure

In a region accustomed to highway-choking snowstorms, this one is being called one of the worst in memory. Snow blown by strong winds forced the closing of a 212-kilometre stretch of the Thruway, the main highway across New York state.

In New Hampshire and elsewhere, icy roads led to accidents. Lake-effect storms in Michigan produced gale-force winds and as much as 46 centimetres of snow, and cancelled several flights at the Grand Rapids airport.

Buffalo snow

A lake-effect snow storm with freezing temperatures produces a wall of snow travelling over Lake Erie into Buffalo. (Gary Wiepert/Reuters)

Schools closed in the North Carolina mountains amid blustery winds and ice-coated roads. In Indiana, three firefighters were hurt when a semitrailer hit a fire truck on a snowy highway.

In Atlanta, tourists Morten and Annette Larsen from Copenhagen were caught off-guard by the freezing weather as they took photos of a monument to the 1996 Summer Olympics at Centennial Olympic Park.

With files from Reuters