The October 2024 DANA event, an isolated high-altitude low-pressure system, occurred between late October and early November, fed by an overheated Mediterranean Sea. The high sea surface temperatures played a key role in the rainfall intensity, with the North Atlantic also exceptionally warm, contributing to greater moisture availability. Precipitation on the day of the event would have been up to 40% lower without the unusually warm seas, and the North Atlantic's contribution increased the episode's intensity by 15%.
In Turís, more than 700 litres per square metre of rain fell in 24 hours, exceeding the average annual rainfall in mainland Spain. Advanced two-dimensional hydraulic modeling of the Poyo–Torrent and Poçalet–Saleta ravine systems revealed flow velocities reaching up to 8 m/s and response times of less than an hour between headwaters and densely populated areas. The V-31 motorway generated backwater effects, worsening flooding upstream.
Rivers, ravines, and wadis evacuated water and sediment to the sea, while flood plains widened river beds, dissipating energy and temporarily storing water. A tool based on hydraulic power was developed to identify trajectories of energetic overtopping flows and aid in locating missing people. Weather forecasts predicted a major storm but failed to pinpoint exactly where and when heavy rainfall would land.
According to a study, climate models accurately capture the impact of a warmer atmosphere holding more moisture but struggle to represent the shift in atmospheric circulation patterns caused by human emissions, which determine where rain falls. In Southern Europe, climate models simulate only around 10% of the observed circulation-driven rainfall trend. Lei Gu from the University of Oxford and colleagues analyzed winter rainfall patterns across the northern hemisphere from 1950 to 2022, studying the influence of a warmer atmosphere and changing circulation patterns.
The findings, published in the journal Nature, indicate that improving the ability to separate natural variation in wind patterns from human-driven climate crisis is central to improving regional rainfall forecasts and providing advance warning of extreme events, helping prevent tragedies like Valencia. Multi-sensor remote sensing using Sentinel-1, Sentinel-2, and Landsat 8 was essential for accurately delineating flood extents and assessing socio-economic impacts. Vital infrastructure such as hospitals, schools, transportation corridors, and agricultural lands were compromised, with peri-urban zones and agricultural areas particularly exposed, reflecting risks from rapid urban expansion into flood-prone plains.
In Valencia, 100,000 wrecked cars remained to be disposed of after the floods. Such extreme climatic processes are likely to occur more frequently in the future due to anthropogenic climate change. The death toll has been reported differently across sources, with some citing over 230 lives lost and others at least 205, possibly due to varying reporting times.
The long-term socio-economic impacts on affected communities and infrastructure remain uncertain, as do the specific improvements needed in climate models to better predict shifts in large-scale wind patterns.