Linking European droughts to year-round weather regimes

Abstract. European droughts have far-reaching socio-economic and ecological impacts, yet their prediction remains challenging due to the complex interplay between regional climate variability and large-scale atmospheric circulation. This study investigates how persistent North Atlantic weather regimes influence the occurrence and spatial distribution of seasonal meteorological droughts across Europe throughout the year. Using reanalysis datasets and a tailored regionalization based on drought synchronicity, we identify six coherent European sub-regions and relate drought events, defined by the standardized precipitation index (SPI3), to year-round weather regimes derived from 500 hPa geopotential height anomalies. Our analysis shows that while each weather regime exhibits distinctive and seasonally consistent precipitation patterns, only a fraction of droughts—primarily in western Europe and during winter—can be directly attributed to anomalies in regime frequency. The findings underline the partial but regionally significant role of North Atlantic circulation patterns in shaping European drought risk, highlighting opportunities and limitations for improving drought forecasts on sub-seasonal to seasonal timescales. This study emphasizes the added value of using year-round weather regimes as a unifying framework for understanding drought drivers, overcoming the constraints of purely seasonal classifications. Improved understanding of these links could help refine climate models and support more robust early-warning systems for drought management across diverse European climates.