The month of January is named after the roman god Janus – the god with two faces that can see to either side at the same time. This god represented new beginnings, and in 154. BC the Roman senate decided that this would be the first month of the year. At the same time in the north, we had our own traditions.
We counted the months after the moon. Following the lunar cycle the month of January, which was called Glugmåned lasted from 14th of December to 12th of January. Glug is a small window to look through, usually without glass, and this month was seen as a peek into the new year.
I have to say that appeals to me, since it means I have still two more weeks of peeking into 2015!