Given the widespread tornado, hail, and wind damage across the central and eastern United States, Aon has suggested that the May 14–17 outbreak could rank among the costliest severe weather events in U.S. history when adjusted for inflation.
In a new report, Aon examined the meteorological drivers and impacts of two major severe weather outbreaks that affected the central and eastern United States between May 14–17 and May 18–20.
According to the firm, the May 14-17 storms were particularly devastating, resulting in extensive tornado and hail damage and 30 fatalities across the Ohio River Valley and Midwest. Notably, a powerful EF-3 tornado wrecked parts of St. Louis, Missouri, severely damaging thousands of buildings.
With this in mind, Aon has stated that total economic and insured losses from the May 14-17 severe weather outbreak will likely reach well into the single-digit billions USD.
“A large portion of this loss will likely come from the St. Louis tornado alone as city officials initially estimate around $1.6 billion in total damages,” the firm explained.
Additionally, Aon suggested that due to multiple significant tornadoes and widespread wind impacts, total economic and insured losses from the May 18-20 severe weather outbreak may also reach into the billions USD.
“As a result, both outbreaks over the past week are already among the costliest severe weather events thus far in 2025,” Aon said.
For comparison, the March 14-16 outbreak earlier this year already ranks as the 7th costliest severe weather event in U.S. history, according to loss data provided by Aon Catastrophe Insight, which you can see in the table below.
Providing more background on the May outbreaks, BMS Group Senior Meteorologist Andrew Siffert recently took to LinkedIn, writing, “Over the last few weeks, an omega block has controlled much of the weather pattern across the U.S., which has limited severe weather across much of the Central and Northern Plains, increasing the wildfire concern over the region.
“With the breakdown of this omega block, the severe weather season is back. There will likely be three weeks of heightened severe weather, with a series of storm systems adding to the insurance industry’s losses in 2025.”
Siffert added, “After a relatively quiet few weeks of severe weather across the U.S., severe weather is back with what is likely the most significant outbreak of severe weather that will cost the insurance industry over $5 billion+ in damages, making it likely the most costly severe weather event so far in 2025 after more severe weather damages occur today as severe weather moves over an even more populated area along the Mid-Atlantic and Ohio River Valley.”
Cotality also recently released a report on the event, estimating that approximately 63,000 properties may have been damaged nationwide, with total reconstruction costs nearing $16 billion.
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