Within a matter of hours, the extreme heat that had been tormenting northern Italy for weeks gave way to exceptional rainfall, flooding and a sharp drop in temperatures. The regions hit hardest were Liguria, Lombardy and the northern part of Tuscany.
The disturbance that swept in was "fuelled" by a marine heatwave that pushed the Mediterranean above 33 degrees Celsius off the Spanish island of Majorca, according to data recorded by a buoy operated by the Aemet meteorological agency (source in Italian). When the first flow of cooler, more unstable air met the hot air masses lingering over northern regions, together with the humidity picked up from the sea, it triggered the first extreme events of the late-summer period.
