Climate security

What happened to winter? And where's the polar vortex?

If you're wondering what happened to winter, you're not alone.

The first two months of winter – December and January – were the warmest on record across the U.S., the National Oceanic and Atmospheric Administration says.

In fact, dozens of cities east of the Mississippi River were reporting one of their warmest winters to date from Dec. 1 through Feb. 17, according to the Southeast Regional Climate Center.  

And all of the big cities of the Northeast and mid-Atlantic, from Boston to Washington, D.C., have seen less snow than usual.

We can thank an unusually strong polar vortex for our mild winter: It kept the arctic air locked in across the polar regions rather than plunging southward into the U.S., the Weather Channel said.  

The polar vortex – everyone's favorite wintertime whipping boy – is a large area of cold air high up in the atmosphere that normally spins over the North Pole (as its name suggests). The stronger the polar vortex, the milder our winter is.