The Mediterranean basin recorded one of its hottest Julys ever in 2026, with average sea-surface temperatures reaching 27°C and peaks more than 3.9°C above normal along the Tuscan coast. Analyses by the LaMMA-CNR Consortium and Italian research centers show that the anomaly extends well below the surface: in the Ligurian Sea, excess heat reaches depths of up to 70 meters, storing an amount of thermal energy equivalent to around 1.8 times Italy’s total final energy consumption in 2024. This enormous heat reservoir does not automatically mean a general weather alert or guarantee sudden floods, but it is altering the atmospheric balance. The warm water is capable of releasing additional moisture and energy into autumn weather systems, increasing the potential for intense thunderstorms and extreme events when different air masses collide. Forecasts from the Italian Air Force Meteorological Service and European climate models point to an autumn in Italy characterized by above-average temperatures and initially limited rainfall in the Centre-North, against a highly uneven water balance between dry soils and the risk of intense localized runoff. The situation calls for close monitoring, highlighting how Italian seas have increasingly become a thermal engine influencing the climate of the wider European continent.