U.S. Climate Extremes Index 1910-2020

The U.S. CEI is based on an aggregate set of conventional climate extreme indicators, including: Monthly max and min temperature, Daily precipitation, Monthly Palmer Drought Severity Index, Landfalling tropical storm and hurricane windy velocity, Tropical cyclone indicator.

A value of 0% for the CEI, the lower limit, indicates that no portion of the period of record was subject to any of the extremes of temperature or precipitation considered in the index. In contrast, a value of 100% would mean that the entire country had extreme conditions throughout the year for each of the indicators considered in the index.
Source: National Centers for Environmental Information Get the data