In this study, we elucidated the regional variability of a trend in cumulative snowfall by analyzing of meteorological data that were observed at 109 meteorological stations from 1962 to 2009. In addition, we discussed about the meteorological conditions that affected the long term variation of cumulative snowfall.
A significant increase in the cumulative snowfall was observed only at Suttu(western Hokkaido), and significant decreases in the cumulative snowfall were observed in the Japan Sea side of Tohoku district, Hokuriku district and the Western Japan. These areas were classified into two types: the transition area and the genial area, respectively. The precipitation (snow or rain) in the transition area was susceptible to change with an increase of temperature. In the genial area, the air temperature during winter season was higher than the temperature that discriminated between snow and rain.
In the transition area, the trends of secular change of cumulative snowfall differed between the Pacific side and the Japan Sea side. The snowfall in the Japan Sea side was mainly caused by the winter monsoon. Therefore, increasing of temperature in the winter season was considered to reduce the cumulative snowfall significantly in this side.
In the genial area, passing patterns of cyclones differentiated whether cumulative snowfall decreased significantly. In the areas where the cumulative snowfall had decreased significantly, the pressure pattern of pair of extratropical yclones mainly provided snow. Thus, decreasing of a number of this pressure pattern was considered to reduce the cumulative snowfall in the areas.

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