ENSO Impact on Summer and Fall Temperatures in Western Europe

El Niño-Southern Oscillation (ENSO) is the main predictor of global climate variability at interannual time scales. Its impact on European precipitation variability has been deeply studied, but not so much its impact on temperature. Recent studies suggest that the increasing intensity in heatwaves seems to be related to the interannual variability of the mean temperature. Therefore, the predictability of temperature could be very useful for the future adaptation to potentially severe heatwaves. In this study, we investigate the impact of ENSO on maximum and minimum temperature throughout the whole seasonal cycle with the aim of finding some predictability and trends. Due to the observed changing teleconnection between ENSO and remote regions, we consider the possible nonlinear and nonstationary relationship as well. For our study, we choose a region in western Europe that has experienced intense heatwaves, and which is also the main region of air temperature interannual variability in Europe. We found a nonseasonal, nonlinear and nonstationary impact. During decades prior to 1980s, warmer conditions are related to La Niña events in summer. Nevertheless, El Niño events seem to be linked to the increase in fall temperatures during decades after the 1980s. These warmer conditions are found to be correlated as well with ENSO characteristics from previous seasons, which suggest a potential source for improving the seasonal forecast. We analyze the underlying dynamical mechanisms of the detected teleconnection, and we found a circumglobal response for summer and an arching-like pattern in fall. Finally, we investigate the possible reasons explaining this variable impact among seasons and decades.