Extreme cold hits Canada and the US

Large parts of the US and Canada are experiencing dangerously cold temperatures as Arctic air plunges southwards.

The US National Weather Service has warned of 'life threatening cold' with temperatures falling to around -40C (-40F) in north-eastern Montana. Wind chills of -34C to -51C (-30F to -60F) are forecast across the Northern Plains with sub-zero wind chills likely as far south as Texas.

Bismarck in North Dakota recorded a temperature of -38.9C (-38.02F), its lowest since 2009. Recent snowfalls in Montreal have seen two of the 10 snowiest days on record in the city, with 36.8cm (14.4in) recorded on Sunday.

An area of heavy snow is expected to track east from parts of Kansas and Missouri reaching south-eastern Virginia and North Carolina on Wednesday. Freezing rain is expected in south-eastern North Carolina and heavy rain is forecast near the Gulf Coast.