It has been ridiculously warm across the eastern half of the country this month, with many spots likely to see their warmest December on record. New York City may reach as high as 72°F on Christmas Eve. Washington D.C. is forecast to reach the mid-70s, and Miami the mid-80s. One of the factors behind this decidedly un-Christmas-like weather is a feature that came to be associated with the brutally cold winters of the past few years: the infamous polar vortex.
