Flooding resulted from the passage of two Genoa low pressure systems (named Hanne and Ilse by the Free University of Berlin) which brought warm moist air from the Mediterranean northwards. The effects of El Niño are believed to have possibly contributed although others disagree. The floods started with heavy rainfall in the Eastern Alps, which resulted in floods in Northern Italy, Bavaria and the Austrian states of Salzburg and Upper Austria. The floods gradually moved eastwards along the Danube, although the damage in the large cities on its shores was not as severe as in the areas affected by the floods later.