"Quick doodle of the Roman god of beginnings and transitions, gates, doors, passages, endings and time. He is usually depicted as having two faces, since he looks to the future and to the past. The Romans named the month of January (Ianuarius) in his honor."
Credit Códice Tuna Colectivo de Arte/Flickr
Perhaps Janus is indeed looking to the future and the past.
And then again, maybe he's looking at the below-normal first half of the month (average temperature 4 degrees) and the above normal second half of the month (average temperature 30 degrees).