CatIQ has published its sixth and final loss estimate for the flooding caused by the remnants of Hurricane Debby, which hit Ontario and Quebec in August 2024.
The two-year post-event figure stands at $2.8 billion, essentially unchanged from the one-year estimate of $2.806 billion. The number covers commercial and residential property claims as well as vehicle claims, including loss adjustment expenses.
Debby is the last of 2024's $4-billion-catastrophes to reach its final tally.
Between mid-July and early August that year, Canada recorded four separate events that each caused over $1 billion in insured damage within a span of 27 days: the Southern Ontario flash flooding in July ($990 million), the Jasper wildfire in late July ($1.304 billion, per its own final estimate published last month), Debby's flooding in early August ($2.8 billion), and the Calgary hailstorm days later ($3 billion). Combined, those four events drove Canada's full-year 2024 insured catastrophe losses to a record $8.5 billion, still the costliest year on record.
Caroline Floyd, director at CatIQ, said Debby's claims have closed faster and more completely than any other event from that record-setting month.
"It is encouraging to see that at the two-year estimate the personal property claims are more than 99 percent closed with just a few outstanding," Floyd said, adding that Debby now has the highest percentage of incurred losses closed of any of 2024's four billion-dollar events. She also noted that the average commercial claim from Debby's Quebec flooding came in close to the average commercial claim from the Southern Ontario flash flooding the same summer, even though the two events struck different regions weeks apart, while the average personal claim in Quebec shrank slightly between the one-year and two-year estimates.
More than 100 millimetres of rain fell across a wide swath of the affected region as Debby's remnants moved through the Lower Great Lakes and along the St. Lawrence River, with parts of southern Quebec recording over 200 millimetres.
Earlier CatIQ estimates found the event generated more than 75,000 personal property claims in Quebec alone, nearly four times the claims volume from the Southern Ontario flooding despite similar average claim sizes.
Debby's stability between the one-year and two-year marks is the exception, not the rule, in Canadian catastrophe loss development.
Jasper's final estimate, published last month, also held steady at its two-year mark, but earlier estimates for both events climbed meaningfully between their initial post-event figures and their one-year updates, largely on commercial claim development.
For brokers advising commercial clients on reserve adequacy or excess coverage after a major regional loss, that pattern is the practical lesson: initial post-event loss figures, including the ones CatIQ itself publishes within days or weeks of an event, consistently understate where commercial claims eventually land, even when personal property claims close out close to their early estimates.
Floyd noted that 2024 has become the industry's reference point for gauging every subsequent catastrophe year, adding that "it only takes one or two events to make it an active year."
That framing lands squarely in the middle of a 2026 season that is testing exactly that observation.
CatIQ's own estimate for June's Saskatchewan and Manitoba storm outbreak has already climbed to $850 million, and British Columbia is currently managing an active wildfire season that has forced tens of thousands of evacuations and destroyed homes near Summerland, with no loss estimate yet available.
Debby's final number closes the book on 2024, but Floyd's comment is really a reminder that Canada's insurance industry no longer treats a record-breaking catastrophe year as an anomaly to plan around. It treats it as the baseline.
