Projecting Summer Hydroclimate Extremes in Central Europe from Winter NAO

Summer droughts have become more frequent and severe in Central Europe, threatening water security and ecosystem resilience. In this study, we examine the link between large-scale climate variability, particularly the winter North Atlantic Oscillation (NAO), and summer hydroclimate and drought propagation across the region. We combine teleconnection diagnostics, reanalysis data, and a process-based, isotope-enabled ecohydrological model to assess how winter NAO variability influences summer droughts and their propagation through the Soil–Plant–Atmosphere Continuum (SPAC) within a representative lowland catchment in the North European Plain. Positive NAO phases in winter are associated with reduced summer precipitation and sustained deficits in soil moisture, streamflow and groundwater, indicating hydrological responses with a lag of up to ten months. We also found that winter precipitation has become less sensitive to NAO variability, while summer droughts are now more strongly linked to preceding positive winter NAO phases, likely reflecting climate-driven changes in atmospheric circulation. Integrating large-scale atmospheric variability with local ecohydrological processes sheds new light on how internal climate modes modulate drought propagation and provides new opportunities to improve seasonal drought prediction and adaptive water-resource planning in Europe’s drought-sensitive landscapes.