Fatal winter storm leaves millions without power in North America with -45C temperatures

More than one million Americans and Canadians are facing Christmas Day without power as a massive winter storm continues to pummel North America. A bomb cyclone, when atmospheric pressure plummets, has brought snow, strong winds and freezing temperatures. Nearly 250 million are affected, and at least 19 deaths have been linked to the storm that extends more than 2,000 miles (3,200km) from Quebec to Texas. Thousands of flights have been cancelled during the festive period. The western US state of Montana is the worst hit by the cold, with temperatures dropping to -50F (-45C).