A powerful Arctic winter storm is making its way through the US and parts of Canada, bringing with it frigid temperatures and flight delays ahead of the busiest travel days of the year.
More than 100 million people across the US are under winter weather alerts, and snowy conditions are expected to wreak travel chaos this weekend.
Major airports have already cancelled flights in anticipation of the storm.
The cold snap could bring the coldest Christmas in decades, say forecasters.
The National Weather Service (NWS) said bone-chilling temperatures of -50F (-45C) and -70F were possible by the end of this week in some parts of the country.
Meteorologists say the winter storm could become a “bomb cyclone” – an unofficial term for a certain type of powerful, rapidly strengthening storm – by Friday.