Dozens of flights were cancelled and several airports temporarily closed due to lightning strikes and strong winds.
High streets were submerged, cars were seen sinking, and train services were suspended, including the R15 line due to a collapsed wall.
Firefighters responded to nearly 400 incidents, with the highest rainfall recorded at 81.7 litres per square metre in Caldes de Montbui.
A flood alert was issued, advising residents to take extreme precautions, and a pre-alert remains for continued heavy rainfall in northeastern Catalonia.