A blast of Arctic air is set to cover much of the United States with temperatures below freezing starting on Friday and into next week, impacting millions of Americans in nearly all of the contiguous states.

However, a deep freeze, thanks to the polar vortex dipping down from Siberia, is about to bring even harsher arctic blast to nearly 300 million Americans starting this weekend. Maps show where and when the cold front will arrive.

Intense snowy wintry weather in the US has been fuelled by activity of the polar vortex, slipping down to engulf large parts of the country. Early January's winter storm prompted seven states to declare states of emergency,