U.S. Climate Extremes Index

The Climate Extremes Index (CEI) is a study prepared by and available from the National Climatic Data Center (NCDC). The CEI was first presented in 1995 as a framework for quantifying observed changes in climate within the contiguous United States. The index is based on an aggregate set of conventional climate extreme indicators which now includes extremes in land- falling tropical storm and hurricane wind intensity. Originally, the CEI was calculated on an annual basis, and now the revised CEI is evaluated for eight standard seasons: spring, summer, autumn, winter, annual, cold season, warm season, and hurricane season. Additional temperature and precipitation stations have been added to the analysis to improve spatial coverage without compromising completeness of data. Near real-time data have also been incorporated into the index, which allow the CEI to be calculated operationally on a seasonal basis.