Tornado Damage and Frequency: An Update Through 2025
No upward trends in normalized tornado losses or in major tornado incidence
Through yesterday, according to preliminary data from the National Oceanic and Atmospheric Administration (NOAA) Storm Prediction Center (SPC), the U.S. has experienced 365 tornadoes, just four above the longer-term average to date. Last year, more than 1,900 tornadoes were observed, the most since 2011, and well above the longer-term average.
Today, I share the latest data on normalized U.S. tornado losses since 1954 and a time series of the incidence of the strongest tornadoes since 1975. I doubt you’ll come across these data anywhere else.
Comparing tornado losses across decades is not straightforward. A tornado striking what was a rural county 70 years ago would cause far less damage than the same tornado striking that same heavily developed county today — because there is now more property and wealth exposed to loss.
To make meaningful historical comparisons of loss estimates, researchers “normalize” losses: they ask what each historical storm or event would cost if it occurred under today’s societal conditions, adjusting for factors such as inflation, wealth, building types and counts, population, and, in some cases, efforts to improve building quality.
This approach was first applied systematically to tornadoes by Simmons, Sutter & Pielke Jr. (2013), which analyzed NOAA SPC data from 1950 through 2011. Zhang et al. (2023) reproduced and extended the Simmons series through 2018, confirming the earlier results and updating the time series. They concluded: “[O]ur results suggest a downward trend in tornado losses for the U.S. as a nation.”
The figure below shows my replication of the Zhang et al. tornado normalization from primary data and extends it through 2025. The normalized losses are expressed in 2026 dollars.
The dominant loss years are 1954 ($36 billion),1965 ($44 billion), and 1974 ($29 billion). The largest recent loss year is 2011 at $16 billion — the largest post-1980 value and the only recent year approaching the scale of the 1960s–1970s peaks. Since 2012, annual normalized losses have largely remained below $5 billion.
The time series shows a significant decrease in annual normalized losses.The 1954–1963 decade averaged $4.8 billion per year; the 2015–2025 decade averaged $1.9 billion per year.
Our 2013 paper identified this trend:
“We can definitively state that there is no evidence of increasing normalized tornado damage or incidence on climatic time scales.”
At the time, we hypothesized that underlying the decrease may be an actual reduction in severe tornado incidence. However, because economic data should not be used to infer trends in related climate variables, we suggested that any such trend in tornadoes would depend upon analyses of climate data.
More than a decade later, tornado data is strongly suggestive of an overall decline in the incidence of the strongest tornadoes. The figure below shows the annual count of F3/EF3 and stronger tornadoes from 1975 through 2024, the period over which data quality is most consistent.
The time series shows a clear decrease in major tornado incidence. The 1975–1984 decade averaged 49 F/EF3+ tornadoes per year; the 2015–2024 decade averaged 26 per year — a decline of roughly 46 percent. Note that data available back to 1954 makes this decrease look much larger, but is accompanied by questions of data quality.
The interpretation of this declining trend requires caution for several reasons. First, the Enhanced Fujita (EF) scale introduced in 2007 changed rating methodology, creating a potential discontinuity in the series. Most analysts believe EF ratings are somewhat more conservative than legacy F ratings for comparable damage, which could contribute to the apparent post-2007 decline. Second, improved public warnings and storm-resistant construction may have contributed to changing the nature of observable damage markers that drive intensity ratings, which are often established based on damage patterns rather than direct measurements of tornado intensity.
Neither of these caveats undermines the the fact that there is no evidence of an increase in violent tornado incidence over the observational record. The IPCC Sixth Assessment Report concluded with low confidence in the detection of any trend in tornado frequency or intensity at the global or regional level, and with low confidence in attribution of any observed changes to anthropogenic forcing. The data reviewed here are consistent with that assessment.
Several hypotheses have been offered in the literature for how accumulating greenhouse gases in the atmosphere may influence tornado behavior. Some commonly cited examples include:
Reduced wind shear. Trapp & Hoogewind (2018) proposed that Arctic amplification could weaken lower-tropospheric wind shear, reducing the environmental favorability for supercell formation. If correct, this would represent a climate signal leading to fewer strong tornadoes.
Geographic shift eastward. Gensini & Brooks (2018) documented a westward decline and eastward increase in tornado activity — a shift toward “Dixie Alley” and away from the traditional “Tornado Alley.” An eastern shift moves tornado tracks closer to higher-density development. They conclude: “At this point, it is unclear whether the observed trends in tornado environment and report frequency are due to natural variability or being altered by anthropogenic forcing on the climate system.”
Increased variability. Brooks, Carbin & Marsh (2014) argued that over 1954 to 2013 tornado activity became more variable — with years of very high activity alternating with years of historically low counts — rather than showing a simple trend in frequency. They explain: “At this point, we cannot offer a physical hypothesis for the increased variability.”
The normalized loss series and the F/EF3+ incidence series both show the same pattern: no upward trend, and arguably, a significant downward trend that has contributed to lower normalized damage levels in recent decades.
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Note: For paid subscribers, a full replication spreadsheet with all annual data, normalization factors, and source documentation is available for download at the bottom of this post.
Technical notes: The normalization factors in the replication, as in Zhang et al., are taken directly from the Weinkle et al. (2018) supplementary data file. They match: For instance, my replicated 1978 normalization factor of 8.195 matches the value of 8.195 of Zhang et al.. For 2019 through 2025 I extend the replicated normalization using the BEA fixed assets series (FRED K1WTOTL1ES000), the BEA GDP implicit price deflator (FRED A191RD3A086NBEA), and Census Bureau population estimates. A full replication spreadsheet can be found at the bottom of this post.
For pre-1996 events, the SPC database records losses in ordinal bins rather than dollar amounts. Following Simmons et al. (2013) Table 1, we assign each event the midpoint of its bin interval (e.g., bin 7: $27.5 million midpoint for the $5M–$50M range; bin 8: $275 million for the $50M–$500M range). This produces a small systematic underestimate for the highest-loss years because these bin distributions are right-skewed — Zhang et al. used MLE-adjusted expected values, which run roughly 20 percent higher for major outbreak years like 1965 and 2011. All values in the figure below are expressed in 2026 dollars, using a BEA GDP deflator ratio of 1.329 applied to the 2018-base normalized series.
One significant data quality issue that I have corrected: The SPC database records only $13.5 million in losses for the December 10–11, 2021 quad-state outbreak — the deadliest U.S. tornado event since 2011. This reflects an incomplete NWS Storm Data submission at the time the database was compiled, not the actual damage. Based on the Karen Clark & Company insured loss estimate of $3 billion (covering tornado, wind, and hail, though KCC noted the event was “driven by pure tornado claims” with limited hail contribution). I substitute a nominal estimate of $6 billion — twice the KCC all-peril insured figure, reflecting uninsured and indirect losses. For 2025, I use NOAA SPC reported $1.9 billion in property damage through November 2025, rounded to $2 billion. None of the conclusionspresented in this post are sensitive to these assumptions.
All quantitative analyses performed by Claude Sonnet 4.6 at my direction.
For Further Reading
Ashley, W. S., Haberlie, A. M., & Gensini, V. A. (2023). The future of supercells in the United States. Bulletin of the American Meteorological Society, 104(1), E83–E105. https://doi.org/10.1175/BAMS-D-22-0126.1
Brooks, H. E., Carbin, G. W., & Marsh, P. T. (2014). Increased variability of tornado occurrence in the United States. Science, 346(6207), 349–352.
Gensini, V. A., & Brooks, H. E. (2018). Spatial trends in United States tornado frequency. npj Climate and Atmospheric Science, 1, 38.
Simmons, K. M., Sutter, D., & Pielke, R. Jr. (2013). Normalized tornado damage in the United States: 1950–2011. Environmental Hazards, 12(2), 132–147.
Trapp, R. J., & Hoogewind, K. A. (2018). Exploring a possible connection between U.S. tornado activity and Arctic sea ice. Journal of Climate, 31(2), 571–587.
Verbout, S. M., Brooks, H. E., Leslie, L. M., & Schultz, D. M. (2006). Evolution of the U.S. tornado database: 1954–2003. Weather and Forecasting, 21(1), 86–93.
Zhang, Y., et al. (2023). Time trends in losses from major tornadoes in the United States. Weather and Climate Extremes, 41, 100639.
Note: For paid subscribers, a full replication spreadsheet with all annual data, normalization factors, and source documentation is available for download below.
