OnRe Underwriting Commentary: 02 November 2026

As we enter November, underwriters may be forgiven for breathing a sigh of relief as the 2026 hurricane season enters its closing period. In fact, we need to go back to 1985, when Category 2 Hurricane Kate made a November landfall in Florida. Whilst warm sea temperatures in the Gulf fuelled Kate to a maximum intensity of Category 3, HURDAT has no record of a Category 3 landfall on the continental United States this late in the season. Memories of 2012's Hurricane Sandy, however, remind us that late-season storms remain a possibility.

Underwriters must also remain vigilant to other perils and territories. Recent history has taught us to be more mindful of wildfires, and earthquakes pay little heed to short-term seasonality patterns.

As the North Atlantic hurricane season closes, the European winter storm season begins to ramp up. Whilst generally posing lower financial severity, major historical storms such as Daria in 1990 and Lothar and Martin in 1999 can have a particular impact on the smooth running of January renewals, happening as they do so late in the calendar year.

Similarly, the financial impact of winter storms in the United States has required greater consideration as regions less used to colder weather have been exposed to extreme polar vortex behaviour. The same phenomenon that has limited 2026 hurricane activity may increase the risk of winter storms. Commentators may point to the "unique" contribution of faulty infrastructure in inflating financial losses from 2021's Uri, but this in turn raises questions about the interaction of a changing climate, expanding exposure, and continuing claims inflation.

How Seasonality Influences Underwriting

These seasonal patterns are reflected in how we assess risk and estimate losses across our underwriting portfolio. For all deals, we model expected loss by the various perils and regions covered. Certain perils, such as earthquake and man-made perils, have a uniform distribution across the calendar year, while others are seasonal.

However, there are additional considerations when estimating losses to a particular deal. For many of our hurricane-exposed deals, our exposure sits at a level where we would need a major hurricane to cause a loss. Further analysis shows that the seasonality of major hurricanes since 1925 (Category 3 and above) has a different pattern from that of all hurricanes.

For each deal, we estimate loss seasonality weighted by its contribution to the expected loss. As each deal has different coverage, structure, and exposure characteristics, loss seasonality can vary significantly from deal to deal.

We must also consider the structure of a deal. Aggregate and subsequent-event deals have a delayed seasonality pattern, as they require multiple events to trigger a loss. Claims development, delayed reporting, and potential capital trapping are also factored into our assessment of earnings.

As such, premium is earned throughout the term of a deal, with little earned on day one, accelerating through periods of higher loss seasonality and culminating upon the release of liability and funds from the deal trust account. At a portfolio level, the different earnings patterns and inception dates of each deal contribute to a more balanced earnings profile.

For these reasons, underwriters, analysts, meteorologists, engineers, and numerous other professionals must continue to work together to further our knowledge of the unknown. Sharing expertise, access to detailed data (thank you, HURDAT, and many others), curiosity, and collaboration are essential as we expand our understanding as a company and an industry.

New capital avenues and mechanisms are equally essential if the industry is to continue to meet the insurance requirements of the new exposures and risks we face as a society.

Ben Fortune
‍Chief Underwriting Officer, OnRe