It’s really, really cold again – as the US shivers through at least the eighth blast of air from the Arctic this winter. Here’s why it keeps happening.

The tenth and coldest polar vortex of the season is blasting across the US this week. More than 58million Americans are under National Weather Service cold warnings from the US-Canada border to as far south as Texas.

Meteorologists warn that the coldest burst of Arctic air this season is coming to put an icy and prolonged exclamation point on America’s winter of repeated polar vortex invasions starting this weeken