The 2025–26 European windstorm season has highlighted the importance of regional concentration, flooding and multi-peril exposure for insurers and reinsurers, according to Marsh Re, the reinsurance broking and advisory business of Marsh.
While the season produced significant losses in Spain and Portugal, Marsh Re says it does not necessarily signal a fundamental change in European windstorm activity. The company identified 21 storms during the season, compared with a historical average of around 22, while activity in northern Europe was also slightly below average.
The notable feature was where the losses occurred. Seven named storms affected Spain and Portugal, with several bringing strong winds and heavy rainfall. Storm Kristin generated an estimated €1.727 billion in insured losses, while Storm Ulrike/Nils resulted in €695 million of insured losses in France, based on data cited by Marsh Re.
For reinsurers, the season highlights the importance of looking beyond windstorm frequency. Marsh Re says a significant proportion of insured losses in the Iberian Peninsula resulted from rainfall and flooding, meaning the overall loss picture cannot be explained by wind activity alone.
A combination of a south-shifted jet stream, atmospheric rivers and repeated heavy rainfall contributed to flooding across Spain, Portugal and parts of France. Marsh Re expects extreme rainfall and associated flash-flood risk to increase in a warming climate, although future changes in windstorm frequency and severity remain uncertain.
Natural variability remains a major influence on year-to-year European windstorm activity, according to Marsh Re. The North Atlantic Oscillation also influenced conditions during the season, but the company found that it could not alone explain the persistence of southern European storm activity.
For reinsurance portfolios, the experience demonstrates how a season can generate substantial losses through the combination of wind, rainfall and flooding without necessarily representing a broader increase in European windstorm frequency. Marsh Re also highlights the influence of factors such as inflation, population growth, exposure, vulnerability and flood defences on insured losses.
The experience is particularly significant for Portugal. Marsh Re estimates that reinsurer losses from the series of storms could reach €1.1 billion to €1.2 billion, compared with around €250 million in premiums from all non-life contracts. The company says this could put pressure on future renewal negotiations following several profitable years for reinsurers since Storm Lesley in 2018.
Marsh Re is also developing new catastrophe models for the Iberian market. Its GCAT Iberian Windstorm and Severe Convective Storm models, alongside an updated Portugal Flood Model, are scheduled for release in early 2027. The models are intended to provide more detailed assessments of wind, severe convective storms and both fluvial and pluvial flooding across Spain and Portugal.
For the reinsurance market, the key takeaway from the 2025–26 season is not necessarily a new European windstorm regime, but the potential for regional and multi-peril events to produce significant losses. Marsh Re expects natural variability to continue driving short- to medium-term windstorm activity, while heavier rainfall and flood-related losses could become increasingly important under a warming climate.
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