Yup, it's cold. Here's an explanation

Temperatures in the east have followed those in the rest of the country, dipping, and staying, well below freezing for the past few days. Why is this happening? Well, it is January. But, as Climate Central explains, we are beginning to understand weather (that's as opposed to climate) a little better. And two things have happened: a "sudden stratospheric warming event" is sending arctic air south, while the Madden-Julian Oscillation has shifted to a phase that favors cold air over the eastern US.

Climate Central's Andrew Freedman quotes Michelle L'Heureux, a climate scientist at NOAA, on the Madden Julian Osciallation:

“The MJO is presently located in a position that favors increased tropical rainfall over the central Pacific (and decreased rainfall over the eastern Indian Ocean-Maritime Continent),” L’Heureux said in an email conversation. “This pattern is most significantly linked to more cold air outbreaks over the eastern U.S.”

She added that it may be too early for the sudden stratospheric warming event's effects to be felt - which means more cold weather ahead. You can read more about the "sudden stratospheric warming event" here. And yes, it's climate change related. According to Climate Central, sudden stratospheric warming events take place in about half of Northern Hemisphere winters, and they have been increasing in frequency.

Image via http://www.intellicast.com/National/Temperature/Current.aspx