A fierce blizzard in the United States has brought on dangerously low temperatures and snow as deep as 43 inches, causing over 30 deaths and leaving more than a million homes without power.
The storm's effects are being felt from the Great Lakes near the Canadian border to Rio Grande near the Mexican border, news agency AP reported.
Buffalo in New York has been the worst hit, with gusting winds and thick snow crippling emergency services.
The extreme cold conditions have been caused by a phenomenon called a "bomb cyclone".
This event occurs when there is a collision between a warm and a cold one air mass, the National Oceanic and Atmospheric Administration said.
In a bomb cyclone or bombogenesis, there is a rapid drop in pressure -- at at least 24 millibars over 24 hours.
The bomb cyclone disrupting life in the US happened when warm air from the gulf of Mexico collided with the cold arctic air. The pressure drop in this case was unprecedented.
"This has led to the development of extreme storm conditions near the core of the low pressure system, with particularly harsh conditions," meteorologist Cyrille Duchesne told news agency AFP.
Climate campaigners say global warming is likely to make bomb cyclones more frequent and intense.
US National Weather Service has warned people against travelling. It said such cold conditions can easily cause frostbite, and in cases of longer exposure, hypothermia and death.
New York governor Kathy Hochul said the storm was the worst-ever seen in the region's history.
"We now have what'll be talked about not just today but for generations (as) the blizzard of '22," she said. "Very dangerous life-threatening situation."
(With inputs from AP and AFP)