Regional hotspots and contrasts in the trends of mean and extreme daily precipitation in France

Study region This study focuses on metropolitan France, a climatically diverse territory where precipitation changes are highly heterogeneous, necessitating detailed, high-resolution analysis across 934 daily rain gauge stations. Study focus Using a non-stationary statistical framework from 1950 to 2022, we analyze changes in wet-day frequency, mean wet-day precipitation, mean all-day precipitation, and 20-year return levels. The methodology captures the evolution of the entire precipitation spectrum across annual, seasonal, and monthly scales. New hydrological insights for the region Results reveal complex, non-uniform trends characterized by widespread summer drying and an overall increase in wet-day frequency, notably in autumn. While mean wet-day precipitation shows slight annual decreases, mean all-day precipitation generally increased, primarily driven by higher wet-day frequency. For extreme precipitation, significant annual increases are concentrated in hotspots including the Rhône Valley, southern Alps, Île-de-France, and Brittany. These contrast with notable decreases in the northern Alps and western Massif Central. The intensification in the south is linked to enhanced moisture transport from a warming Mediterranean Sea, fueling intense autumnal rainfall. These findings underscore a profound spatio-temporal heterogeneity in France’s precipitation regime, providing a high-resolution benchmark crucial for regional climate adaptation, water resource management, and refined flood and drought risk assessments. • We employ a generalized gamma to model the trends in the whole precipitation distribution, conditioned on sea-surface temperature. • The model allowed us to jointly assess trends in mean of wet-days frequency, mean of wet and all-day precipitation, as well as extremes. • Observed trends in France are not uniform, exhibit significant month-to-month variabilities sometimes blurring the long-term trend. • We identified regional hotspots with significant increase in extreme precipitation.