U.S. Disaster Normals

Abstract

The U.S. Disaster Normals offer a standard way to compare state-level losses from natural hazards to historical estimates. Proposed periods of the Disaster Normals correspond directly to NOAA's Climate Normals products, including conventional 30-year Normals (1991-2020), supplemental 15-year Normals (2006-2020), and reference Normals (1961-1990) to allow for concurrent analysis. The underlying direct loss data used for the computation of U.S. Disaster Normals originate from the Spatial Hazard Events and Losses Database for the United States Version 21 (sheldus.org) housed at Arizona State University, originally developed by the Hazards, Vulnerability, and Resilience Institute (HVRI) at the University of South Carolina. Adopting climate normal procedures, U.S. Disaster Normals are computed from annual, seasonal, and monthly loss values during the averaging period. For each of the impact elements (i.e., direct property damage, direct crop damage, direct injuries, direct fatalities, and total losses), three main groups of statistics are generated: 30-year averages, frequencies of occurrence (exceedance), and percentiles. Findings highlight the skewed nature of disaster loss data, thus suggesting median and exceedance values as relevant reference points. For example, states such as California, Texas, Florida, and Louisiana are experiencing more than 11 days per year with direct property loss exceeding $1 million. On average, these states see more than $1 billion in total losses every year.