Multiple rounds of severe thunderstorm activity that struck the Midwest of the United States earlier this month is seen as having the potential to result in a top-10 severe weather insurance industry loss event, which implies that the cost could be around $5.1 billion or higher to the market, according to broker Guy Carpenter.
Between August 9th to 11th, the Midwest was impacted by multiple rounds of severe convective storm (SCS) activity, driven by a slow-moving cold front affecting the states of Wisconsin, Illinois, Iowa, Indiana, Ohio, as well as other surrounding states.
Most notably, reported maximum windspeeds in the southern part of the Chicago, Illinois metropolitan region registered above 90 mph.
However, the strongest wind gust of 97 mph was reportedly recorded in Sugar Grove, IL, a suburb of Chicago.
Reinsurance broker Guy Carpenter explained in its early August 2026 global cat activity report, that multiple states experienced damaging winds with gusts reaching 60-80+ mph, large hail that measured up to 3.5 inches, isolated tornadoes, and heavy rainfall of 2-3 inches per hour, with multi-day totals potentially exceeding 9 inches.
The broker also highlighted that further east several bouts of straight-line wind events across Ohio have transpired within the last 72 hours, while Columbus, Ohio recorded a peak wind gust of 82 mph yesterday.
“Three confirmed tornadoes have been reported in Illinois, and more field surveys continue. With over 200 confirmed tornadoes in 2026, Illinois joins Texas as the second state on record to ever record this level of tornado activity in a year. The Texas record is 245 tornadoes, occurring in 2015,” Guy Carpenter explained.
Guy Carpenter also commented on the potential financial impacts of this severe thunderstorm outbreak in the United States, “Given the severity of winds in the Chicago, Indianapolis, and Columbus, OH metropolitan areas, insured losses are likely to be measured in the billions of dollars.”
The broker added: “It is plausible given initial reports of damage that the last several days of severe weather activity could breach the top ten list.”
Guy Carpenter’s ranking of the top-10 severe convective storm insured loss events in the United States since 1995 can be seen below:
At the bottom of that list is a $5.1 billion industry insured loss event from May 2014.
For this recent event to rank higher it suggests the insurance market could ultimately face around $5.1 billion or more in losses from this series of severe thunderstorms, which suggests that insurers could tap into some reinsurance capital.
This recent thunderstorm outbreak follows July’s severe weather outbreak that impacted the Midwest late in the month, and also led to further storms affecting the eastern United States.
Broker Aon previously indicated that those July events could drive insured losses of around $5 billion or more, suggesting that it may also rank among the top ten severe weather insurance loss events in history.
As a result, recent weeks of US severe weather look set to prove costly for the global insurance and reinsurance industry.
While given the magnitude of industry losses they may cause their could also be implications for erosion of aggregate risk transfer arrangement deductibles, including for any exposed catastrophe bonds.
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