In their study, "Increased persistence of warm and wet winter weather in recent decades in north-western Europe", the authors analyzed historical temperature and precipitation records from weather stations across Europe. Using quantile autoregressive models, the team revealed significant increases in the persistence of both warm weather and precipitation events during winter months in north-western Europe when comparing 1990-2020 with 1950-1980. The study links this heightened persistence to a shift toward unusually strong positive phases of the North Atlantic Oscillation (NAO) index, with recent NAO index values exceeding those simulated by climate models under high greenhouse gas scenarios.
The authors conclude that the increased persistence of warm and wet weather makes prolonged wet spells more likely, thereby heightening flood risk across north-western Europe.