Investigating the Role of Climate Change in the 3 May 2025 Western Europe Hailstorm Using Atmospheric Analogs

ABSTRACT On 3 May 2025, a severe hailstorm affected Paris and parts of western Europe. We assess whether anthropogenic climate change contributed to its intensity using ERA5 reanalyses and an analog‐based attribution framework. The synoptic pattern featured a cut‐off low and a surface cold front. We identify circulation analogs to 3 May 2025 in two periods, that is, a cooler “past” (1974–1999) and a warmer “present” (1999–2024), and compare thermodynamic conditions under otherwise similar large‐scale flow. Hail probability and size are estimated with two models: (i) a logistic formulation using Convective Available Potential Energy (CAPE), deep‐layer wind shear, and convective precipitation, and (ii) an extended model including freezing‐level height and 850 hPa temperature. Models are calibrated with Île‐de‐France observations and validated independently. Present‐day analogs exhibit significantly higher CAPE (+200 J/kg), a higher freezing level (+100–200 m), and similar deep‐layer shear, yielding larger hail probability (+30%) and size (+2 cm). These results indicate that human‐induced warming likely enhanced the hailstorm severity in this synoptic setting.