The summer 2021 Switzerland hailstorms: weather situation, major impacts and unique ­observational data

Abstract

On 28 June and 8 July 2021, all the ingredients for severe convection were present and resulted in severe hailstorms over Switzerland, causing historic damage, as recorded by several insurance companies. The return periods of those events locally exceeded 70–100 years according to the new Swiss hail climatology. A coherent and comprehensive picture of those hailstorms is given by a unique combination of hail observing systems: automatic hail sensors, crowdsourced reports and radar-based algorithms. (Figure: Sturmarchiv Schweiz/www.sturmarchiv.ch © Martin Hotz, Steinhausen.)