On Feb. 20, President Biden declared the state of Texas the site of a major disaster, making available federal funding for the relief of the millions of Texans who have been without water, food, electricity, and even shelter in freezing conditions. The crisis in Texas came as a result of Winter Storm Uri, which swept across the United States, setting thousands of single-day cold or snowfall records, leaving nearly 10 million people without power and killing at least 70.
Unlike hurricanes and earthquakes, there is no widely used scale or index for assessing the impact of snowstorms. In recent years, however, the meteorological community has made several successful attempts to establish a standard for measuring the impact of extreme snow events that can be used to compare snowstorms over time.
The Regional Snowfall Index, introduced in 2014, ranks a snowstorm impact on a scale of 1 to 5 using data on a storm’s area of snowfall, the amount of snowfall, and the population affected. The RSI has since been used to retroactively classify nearly 600 snowstorms that occurred between 1900 and 2013.
To determine the worst blizzards of all time, 24/7 Wall St. ranked snowstorms based on their Regional Snowfall Index values, published by the National Oceanic and Atmospheric Administration’s National Centers for Environmental Information. We included the 25 snowstorms designated as Category 5 since 1900. Data on duration, region, affected area, and affected population also came from the NOAA. 24/7 Wall St. combined data on affected area and population for Category 5 storms that spanned multiple regions, considering it one event. Storm names, as well as measures of snowfall in the affected areas, came from various news and media sources.