Extremely cold temperatures have continued for a second day in the eastern United States.
A number of record lows were broken on February 19, including in Washington, Pittsburgh and Baltimore. Midwest temperatures dropped as low as -40F (-40C).
The polar vortex has been blamed for at least 19 deaths, many in Tennessee where temperatures were far lower than usual.
Forecasters say some areas will see sleet and freezing rain as temperatures warm up slightly over the weekend.
Ontario and parts of Quebec were also under extreme cold warnings – with temperatures dropping to -13F (-25C) in Thunder Bay and -6F (-21C) in Ottawa on February 20.
In Toronto, a three-year-old boy died on February 20 after being lost for hours wearing only a T-shirt, nappy and boots.
Elijah Marsh was found near his home in -2F (-19C) temperatures but died in hospital.
The extreme cold has also frozen parts of the Hudson River in New York and much of Lake Erie and Lake Michigan.
Chicago reopened its schools on February 20 after closing the day before as wind chills made outside feel like -29 (-34C).
About 3,000 people were still without electricity in Tennessee on February 20 down from 30,000. Eleven deaths are being blamed on the cold in the state, including six from hypothermia.
In western Pennsylvania, temperatures dipped to minus -18F (-28C), without the wind chill.
Further north in the mid-western state of Minnesota, temperatures dived into -42F (-41C).
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