This NOAA satellite image taken Sunday, January 05, 2014 at 01:45 PM EST shows widespread clouds affecting the eastern United States as moisture was surging north ahead of developing low pressure in the Ohio Valley
Media playback is unsupported on your device

US weather: BBC explains why it is so cold

Temperatures in parts of the United States could drop to record lows of -30C (-22F) as a result of a "polar vortex" of cold, dense air.

John Hammond from the BBC Weather Centre explains what causes the unusual phenomenon.

  • 06 Jan 2014
Go to next video: Ice-breakers deployed to Lake Michigan