Judging by your username, you might have a travel related site? If so, then it could have to do with that. We run a large travel site and a January increase has always been something to count on. As soon as the new year starts, people tend to start planning trips, etc. for the year ahead.
Mind you, I'm not sure why it "switched off" for you in Feb. Typically we'd see it maybe dip slightly in Feb, but continue to then increase throughout the year, reach a peak in June / July and then start to drop again after the northern hemisphere summer is over in August.