The term 'Dry January' has been around for almost two decades now, but it's not a new concept. Finland launched a Sober January campaign in 1942 as part of their war effort, and the United States had a period with thirteen Dry Januaries (and Februaries, and Marches, ...).
Now, one could argue January is the worst month to hit the pause on Spirits, being the coldest and the dreariest of months, but it makes sense: new year, new you.