It's not so much January as it is WINTER.
With the holidays over, all we have to look forward to is long, cold, and possibly snowy days until possibly April. The sun attempts to breakthrough, but the clouds prevent it.
It's just so much 'blah'.
I kinda wish people kept their Christmas lights on throughout the winter at night to kinda make it feel less drab out, but that obviously people probably don't want to be reminded of the holidays anymore after the insanity they can bring.