My town never (almost never) has a white Christmas. The falling or not falling of snow, then, obviously is related to Christmas and things that look like Christmas. People are just slow at taking down the lights off their houses. Why, on my street alone there are at least three houses that still flip the switch and burn the brights every night! The gods of snow know to stay away until enough of the tinsel comes down and it really looks like the dark of winter. Then it can snow.
I've found additional documentation for the reasoning in this new "fact." Ground Hogs' Day! Here we are nearly at February 2nd, and Nature is looking for clues on how to play her hand. Shadows and Christmas lights tell her what to put in the weather queue--simple as that.
Creating modern-day, crazy folklore keeps me entertained and brightens all the Things I get to do today. And while the skiers are happy with the recent snow on the mountain, unless you want to be the receiver of their frustration over poor ski conditions, get your Christmas lights down now! At least consider making it one of the Things you get to do today.