The underlying causes of the magnitude of these unusual weather features are not completely understood.

Although the meteorological situation that produced the blizzard and other events of winter 1995-96 is fairly well known, it is a more difficult problem to identify the causes of the unusual weather. Typically, one seeks a cause and effect relationship between phenomena that occurs with similar frequency. Given the fact that events like this past winter happen at intervals of several years or longer, they may be linked with interannual to decadal climate fluctuations. At present, our understanding of such variations is limited, particularly when the region of interest lies outside the tropics. There is a theory for the interannual climate variability of the tropics which links a coupled ocean-atmosphere oscillation of the tropical Pacific Ocean with a larger scale fluctuation of atmospheric pressure and precipitation. This is the widely known El Niño phenomenon and the associated Southern Oscillation. For the period from 1990 until early 1995, the El Niño was in its warm phase with tropical Pacific Ocean temperature above normal throughout nearly the whole period (see figure at right). Over the period March 1995 to September 1995, the tropical Pacific switched from a warm anomaly to a cold anomaly and was in its cold phase (sometimes called La Niña) at the time of the blizzard. The possible connection between the tropical Pacific and the extratropics is a topic of current climate research, so it cannot be definitively stated that the La Niña conditions in the tropics were related to the blizzard.

Several observed variations of the extratropical atmosphere are known to be correlated with interannual tropical fluctuations. It is known that the jet stream over North America responds to tropical Pacific anomalies and that precipitation anomalies in parts of the U.S. are significantly correlated with El Niño and La Niña (particularly in southern California and southeastern U.S.). During the winter of 1995-96, several known extratropical variations of the upper troposphere were quite active, and they underwent a significant change at about the time of the east coast blizzard. In particular, a frequently observed fluctuation of the normal winter upper tropospheric flow called the North Atlantic Oscillation was observed to be very strong in its negative phase during most of December 1995 and abruptly switched to its positive phase after about 12 January 1996. This means that there was a quasi-stationary center of high pressure over the North Atlantic (with an accompanying negative departure from normal pressure over Greenland) during the period preceding the blizzard. The high pressure then shifted over Scandinavia for the balance of the month to produce the monthly average shown in the iaccompanying 500mb height map . Such a distribution of pressure in the upper troposphere can persist for several weeks or even months and is called "blocking" by meteorologists. It has been suggested that the larger than normal amplitude of the upper tropospheric wave that was associated with the blizzard was caused by the active Atlantic blocking observed in December and early January.