New model shows wind-only approaches underestimate winter storm losses by at least 5%

A new vulnerability function links over 200,000 Dutch insurance claims with very detailed wind-gust and 24-hour rainfall data to better predict winter storm damage to homes. Instead of looking only at wind, it uses a single statistical model that captures both high winds and heavy rain.

The study shows that relying on wind alone can seriously undercount the true cost of storms. For example, wind-only models miss about 5% of damage when a storm drops 50 millimetres of rain, rising to 21% at 75 millimetres and 57% at 100 millimetres. Another key finding is that more expensive homes lose a smaller percentage of their value, even though their total repair bill (in euros) is higher.

Designed for easy integration into private and open-source catastrophe models, this function gives insurers and policymakers a clearer picture of potential storm losses. As European winter storms grow wetter with climate change, including rainfall in damage estimates will improve premium accuracy, stress testing, and resilience planning.