It's not unheard of for NYC and the northeast to get snow in October. Usually, indeed the vast majority of times apart from the higher elevations and latitudes, it's a trace, just enough to sugar frost the mums.
This weekend was pretty icky. At least a million and a half without power, hundreds of thousands unable to commute to work, tens of thousands more suffering with no heat or hot water (cheap landlords + early freezing = bad situation)