Extreme Weather Sourcebook 2001

Data Sources and Methodology


Extreme weather accounts for many billions of dollars in damage every year in the United States. The size of the U.S., along with its particular geographical and societal conditions, make it susceptible to a wide range of weather phenomena. This report presents a summary of damage suffered from hurricanes, floods, tornadoes, lightning and other weather events in the United States and its territories.

The goal of the report is to educate and stimulate interest in the societal impacts of weather in the United States. To compare damage from different phenomena, recorded over different time intervals, is a challenging methodological task. The data presented in this report come from a variety of sources using a range of methodologies. The data have been adjusted in various ways (described below) to allow for an apples-to-apples comparison of losses between events and over time. Consequently, extreme caution should be exercised when using this data. It is strongly recommended that analyses requiring precise data -- such as trend analysis or investigation of particular events - use the Sourcebook as a starting point to further, more rigorous research. In addition, the information presented here should be understood as historical, not predictive.

Tornado Damage Figures

Data Source

The 1950 - 1999 tornado damage figures for the 50 states and Puerto Rico were compiled from the Storm Events database maintained by the National Climatic Data Center (NCDC). The Storm Events database contains all weather events from 1993 - the present, as entered into the Storm Data publication, as well as tornado data from 1950 through 1992 from the Storm Prediction Center. The Storm Events database was derived from the "Pearson Tornado Tape" database (item 9714). The damage amounts are estimates by the National Weather Service at the time of the report.

The previous version of the Extreme Sourcebook used tornado damage figures from the Tornadoes, Deaths, and Damage by Year, 1950 - 1995 database compiled by the Storm Prediction Center (SPC). The damage figures in the SPC database were adjusted for inflation using the Consumer Price Index (CPI). The updated version of the Extreme Sourcebook uses the Storm Events tornado damage figures which are more current and which have not been adjusted for inflation. The Sourcebook uses a measure other than the CPI to adjust for inflation, described below.


Three adjustments have been made to the tornado damage figures. First, they have been adjusted for inflation to 1999 dollars using the gross national product implicit price deflator found in the Economic Report of the President published annually by the White House. This measure was used instead of the CPI to introduce consistency with the adjustments used for the damage data for other phenomena presented in the Sourcebook.

Second, the damage figures were adjusted for changes in the nation's wealth using the methodology in Pielke and Landsea (1998) 1 as measured by the U.S. Bureau of Economic Analysis's "fixed reproducible tangible wealth" statistic using 1999 as the base year.2

A final adjustment was made for the following reason. Damage from tornadoes between 1950 and 1994 was originally reported in one of nine classes (Class 1 = <$50; Class 2 = $50 - 500; Class 3 = $500 - 5K; Class 4 = $5K - 50K; Class 5 = $50K - 500K; Class 6 = $500K - 5M; Class 7 = $5M - 50M; Class 8 = $50M - 500M; Class 9 = $500M - 5B). These data were entered into the Storm Events database as the upper limit of the damage class, i.e., if the tornado was originally reported as a Class 4 tornado, the Storm Events database reports it as having caused $50,000 in damage. It is unclear why the upper limit of the damage class was chosen. We have adjusted the 1950 - 1994 damage figures to the geometric mean of each damage class. We chose the geometric mean to reflect the midpoint of the damage classes. Storm Events reported 1995 - 1999 damage in actual dollar amounts rather than the upper limit of a damage class, so this final adjustment was not made to these figures.

Storm Events reports property damage from tornadoes for 1950 - 1992, and both property and crop damage from 1993 - on. The state-by-state graphs indicate when crop damage has been reported.


1Compare Brooks, H.E. and C.A. Doswell III, 2000: Normalized damage from major tornadoes in the United States: 1890-1999. Weather and Forecasting (submitted September 2000). Available at http://www.nssl.noaa.gov/~brooks/damage/tdam1.html.

2Select "BEA Products by Subject Area," "Tangible Wealth, 1998," "NDN-0216." The 1998 and 1999 statistics were computed by the authors of this study based on extrapolation of data from the previous 10 years.

Flood Damage Figures

Data Source

The 1955 - 75 flood damage figures for the 50 states were compiled from Climatological Data National Summary, Annual Summary (CDNS) 27(13): 124. The 1983 - 99 flood damage figures for the 50 states, Puerto Rico, and the Virgin Islands were compiled from the 1992 and 1999 U.S. Army Corps of Engineers Annual Flood Damage Report to Congress. Data for 1976 - 1982 are not deemed sufficiently reliable at the state level to include in the present analyses. The damage figures were originally reported in hydrologic years and, beginning in 1983, were reported in fiscal years. Note that flood damage was reported as "zero" in the 1983 - 1990 reports if damage figures were unavailable, even though flooding occurred, and for this reason the annual averages should be intrepreted with caution. The data in this project are the result of an ongoing reanalysis of the nation's flood damage data record, sponsored by the Office of Global Programs of the National Oceanic and Atmospheric Administration.


The flood damage data have been adjusted for inflation and wealth using the same methodology as was used with tornado damages.

Hurricane Damage Figures

Data Source

The 1925 - 1995 hurricane damage figures for the mainland states are derived from Pielke and Landsea (1998), which compiled the data from National Weather Service records. Click here for the complete data set. The original (non-normalized) data set can be found here. Additional data for 1900 - 1924 were provided by Chris Landsea, Hurricane Research Division, NOAA. The 1996 - 1999 damage figures for all states except Hawaii and except Puerto Rico and the Virgin Islands were compiled from the preliminary hurricane and tropical storm reports of the National Hurricane Center.3 If a report listed damage as occuring in more than one state but did not indicate how to apportion damage among the affected states, damage was apportioned equally among the affected states.

Data for Hawaii hurricanes begins in 1950 and were compiled from NOAA's Central North Pacific Hurricane Summaries 1800s - 1996. Data for Puerto Rico and U.S. Virgin Island hurricanes 1900 - 1995 were compiled from The Deadliest, Costliest, and Most Intense United States Hurricanes of this Century,4 for 1996 Hurricane Hortense from the September 1996 volume of Storm Data, and for 1998 - 1999 from preliminary hurricane reports of the National Hurricane Center .

Only damage from storms classified as hurricanes or tropical storms by the National Weather Service-National Hurricane Center has been included. These figures focus on damage due to wind and/or storm surge and usually exclude damage from flooding.


The 1900 - 1999 figures for the mainland U.S. were normalized to 1999 values using the methodology described in Pielke and Landsea (1998). The Hawaii and Puerto Rico/Virgin Islands data have been adjusted only for inflation. Consequently, these states/territories have not been included in the rankings.


3Select "Historical Information," then "Storm Archives." Storms reviewed: Hurricanes Bertha, Fran, Danny, Bonnie, Earl, Georges, Mitch, Brett, Dennis, Floyd, Irene, Jose, and Lenny; Tropical Storms Josephine, Charley, Frances, and Harvey.

4Herbert, P.J., J.D. Jarrell, and M. Mayfield, 1996: Report No. NOAA-TM-NWS-TPC-1, Table 14.

Hail, Thunderstorms, Heavy Rainfall Events, Winter Storms, Lightning, Wind Storms, Federal Disaster Relief for Weather-Caused Events

Data Source

1950 - 1997 national data provided courtesy of Stanley Changnon, Climatologist, 801 Buckthorn Circle, Mahomet, Illinois, 61853.


Where applicable, the data have been adjusted for inflation to 1997 values or as described in the figure.

Lightning Fatalities, Injuries, Casualties, and Damage Reports by State 1959 - 1994

Data Source

Curran, E.B., R.L. Holle, and R.E. Lopez, 2000: Lightning casualties and damages in the United States from 1959 to 1994. J. of Climate 13, 3448 - 3464, Tables 3 and 4.

"Damage reports" refers to every instance in which damage from lightning was reported, regardless of the amount of damage.



For Further Reading

Barnes, J., 1998: Florida's Hurricane History. University of North Carolina Press, Chapel Hill and London. 330 pp.

Barnes, J., 1995: North Carolina's Hurricane History. University of North Carolina Press, Chapel Hill and London. 206 pp.

Brooks, H.E., and C.A. Doswell III, 2000: Normalized damage from major tornadoes in the United States: 1890-1999. Weather and Forecasting (submitted September 2000).

Changnon, D., and S.A. Changnon, 1998: Evaluation of catastrophe data for use in climate change investigations. Climatic Change, 38, 453-445.

Changnon, S.A., 1982: Users beware: The upward trends in tornado frequencies. Weatherwise, 35, 64-69.

E.B. Curran, R.L. Holle, and R.E. Lopez, 2000: Lightning casualties and damages in the United States from 1959 to 1994. J. of Climate, 13, 3448 - 3464.

Grazulis, T.P., 1993: Significant Tornadoes 1680 - 1991: A chronology and analysis of events. The Tornado Project of Environmental Films, St. Johnsbury, Vermont, 1326 pp.

Grazulis, T.P., 1997: Significant Tornadoes Update 1992 - 1995. The Tornado Project of Environmental Films, St. Johnsbury, Vermont, 1444 pp. (continued from original version).

The H. John Heinz III Center for Science, Economics and the Environment, 1999: The Hidden Costs of Coastal Hazards: Implications for Risk Assessment and Mitigation. Island Press, Washington, D.C. 220 pp.

Kithil, R.: Results of investigations into annual U.S.A. lightning costs and losses. National Lightning Safety Institute.

Kunkel, K., R. A. Pielke Jr., S. A. Changnon, 1999: Temporal fluctuations in weather and climate extremes that cause economic and human health impacts: A review. Bull. Amer. Meteor. Soc., 80(6), 1077-1098.

Longshore, D., 2000: Encyclopedia of Hurricanes, Typhoons, and Cyclones. Checkmark Books, N.Y., 372 pp.

Lopez, R.E., R.L. Holle, and T.A. Heitkamp, 1995: Lightning casualties and property damage in Colorado from 1950 to 1991 based on Storm Data. Weather and Forecasting, 10, 114-126.

National Research Council, Committee on Assessing the Costs of Natural Disasters, 1999: The Impacts of Natural Disasters: A Framework for Loss Estimation. National Academy Press, Washington, D.C. 80 pp.

Pielke, R. A., Jr., and M. Downton, 1999: U.S. Trends in streamflow and precipitation: Using societal impact data to address an apparent paradox. Bull. Amer. Meteor. Soc., 80, 1435-1436. Available for download at

Pielke, R.A., Jr., and M. Downton, 2000: Precipitation and damaging floods: Trends in the United States, 1932-1997. J. of Climate, 13(20), 3625-3637.

Pielke, R. A., Jr., and C. W. Landsea, 1998: Normalized hurricane damages in the United States: 1925-1995. Weather and Forecasting, 13, 621-631.

Pielke, R.A., Jr., and C.W. Landsea, 1999: La Niņa, El Niņo, and Atlantic hurricane damages in the United States. Bull. Amer. Meteor. Soc., 80(10), 2027-2033. Available for download at www.esig.ucar.edu/hp_roger.html.

Relevant Links

Extreme weather and climate events (NCDC)

Billion dollar US weather disasters (NCDC)

El Nino/La Nina (NCDC)

Global climate change (NCDC)

Hurricanes (includes maps and special reports on numerous hurricanes) (NCDC)

Heavy precipitation (includes maps--such as 24-hour maximums by state, special reports, etc) (NCDC)

Societal Aspects of Weather (ESIG)

Temperature extremes (includes maps--such as extreme maximum by state, special reports, etc) (NCDC)

Tornadoes (includes maps--such as long-term averages by state and normalized per 10,000 sq miles, special reports, etc) (NCDC)

Weather events (numerous reports on recent and historical events)(NCDC)

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