2013–14 North American winter

The 2013–14 North American winter was extremely active, deadly, record-breaking and bitterly cold for the United States and North America as a whole, due in part to the collapse of the polar vortex in November 2013, which allowed very cold air to travel down into the United States, leading to an extended period of very cold temperatures. The pattern continued mostly uninterrupted throughout the winter and numerous significant winter storms affected the Eastern United States.

Source: Wikipedia — 2013–14 North American winter (CC BY-SA 4.0)