It's not cold, it's painful as polar vortex takes its toll in US

The coldest, most dangerous blast of polar air in decades has gripped the US Midwest and pushed toward the East and South and eastern Canada, closing schools and day care centres, grounding flights and forcing people to pull their hoods and scarves tight to protect exposed skin from nearly instant frostbite.

Many across the nation's midsection went into virtual hibernation, while others dared to venture out in temperatures that plunged well below zero Fahrenheit (minus 18 Celsius) yesterday.

"I'm going to try to make it two blocks without turning into crying man," said Brooks Grace, who was bundling up to do some banking and shopping in downtown Minneapolis, where temperatures reached 23 below F (-31 C), with wind chills of minus 48 F (minus 45 Celsius). "It's not cold, it's painful."

The mercury also dropped into negative territory in Milwaukee, St. Louis and Chicago, which set a record for the date at minus 16 F (minus 27 C).

Wind chills across the region were 40 below F (40 below C) and colder. Records also fell in Oklahoma, Texas and Indiana.

Forecasters said some 187 million people in all could feel the effects of the "polar vortex" by the time it spread across the country last night and today.

Record lows were possible in the East and South, with highs in the single digits F (minus 17 to minus 13 C) expected today in Georgia and Alabama.

Wind chills were expected to reach minus 10 F (minus 23 C) in Atlanta and minus 12 (minus 24 C) in Baltimore.

From the Dakotas to Maryland, schools and day care centres shut down.

For a big swath of the Midwest, the bone-chilling cold moved in behind another winter wallop: more than a foot (30 centimetres) of snow and high winds that made travelling treacherous.

Several deaths were blamed on the snow, ice and cold since Saturday, including the death of a 1-year-old boy who was in a car that went out of control and collided with a snowplow yesterday in Missouri.

It took authorities using 10-ton military vehicles known as "wreckers" until early yesterday to clear all the chain-reaction accidents caused when several semis jackknifed along snowy interstates in southern Illinois.

The crash stranded about 375 vehicles, but there were no fatalities or injuries, largely because motorists either stayed with their cars or were rescued and taken to nearby warming centres if they were low on gas or didn't have enough coats or blankets, said Jonathon Monken, director of the Illinois Emergency Management Agency.