The seemingly weird extremes are directly related to the position of the jet stream. The western and eastern sides of the US fall on opposite sides of a big loop in the jet stream, which is keeping the west hot and dry, while on the eastern side of the country cold air is descending from the Arctic and freezing us.
You can see this better in this NASA video ...
This unusual behavior lead to possibly the best winter jet stream map I have ever seen ...
So when you average things out, nationally January 2014 was the 347th consecutive month (or about 29 years) with temperatures above the 20th-century average! So - stinks for us locally, but nationally things are still warmer than average. And for the earth as a whole, it was the fourth-warmest January on record.
If you want more information,
Visit the NOAA State of the Climate website (http://www.ncdc.noaa.gov/sotc/)
and Phil Platt is all over this, as usual, at Bad Astronomy