List of regional snowfall index category 5 winter storms



The regional snowfall index (RSI) is a system used by NOAA to assess the societal impact of winter storms in the United States. The system is a replacement for the Northeast snowfall impact scale (NESIS) system. Since its initiation, the NCDC has retroactively assigned RSI values to over 500 historical storms since 1900.

Storms are ranked from category 0 ("nuisance") to 5 ("extreme") on the scale. The impact of the storms is assessed in six different regions of the United States: Northeast, Northern Rockies & Plains, Ohio Valley, South, Southeast, and Upper Midwest. A category 5 extreme ranking is indicated by a numerical score of 18 or higher on the scale.

Out of the over 500 historical storms assessed since 1900, only 26 storms have been given a category 5 ranking. The highest ranking storm on the list is the Great Blizzard of 1978, which scored a value of 39.07. The most recent storm to receive a category 5 ranking is the January 2016 United States blizzard, which scored a value of 20.14. The following list orders the storms chronologically.