Exceptionally warm waters around the Balearic Islands supplied extra heat and moisture to the atmosphere, helping fuel intense storms and torrential rainfall across parts of Spain.

Recent torrential rainfall across parts of the Mediterranean was fueled by exceptionally warm waters in the Balearic Sea, which reached their highest recorded temperatures since at least 1940. The unusually warm sea provided additional energy, increased evaporation and contributed to the development of powerful storm systems.

The severe weather prompted Spain’s State Meteorological Agency (Aemet) to issue red alerts for exceptional danger late last Thursday and into Friday morning in Castellón, Tarragona and Valencia. Red warnings were also issued in Murcia on Friday, Girona on Sunday and Barcelona on Monday.

The episode brought more than 200 litres of rain per square metre to some parts of Catalonia between midnight on Saturday and 9 p.m. on Sunday.

In Vilassar de Dalt, near Barcelona, rainfall reached 226 litres per square metre, including 176 litres in just six hours. The Drassanes weather station in Barcelona recorded a further 202 litres.

“These were very intense rainfall events that accumulated over a relatively short period of time,” said Rubén del Campo, an Aemet spokesperson, who highlighted the temperature of the Mediterranean Sea as a significant factor in the episode.

The Balearic Sea Reaches Exceptional Temperatures

The Balearic Sea — the area between Spain’s eastern coast and the Balearic Islands, including Ibiza and Mallorca — rose above 26°C in late September.

According to Del Campo, that is a temperature more typical of late August and was a record for that time of year. There had been no previous record of such a temperature dating back to at least 1940.

The exceptionally warm conditions have not been limited to a few days.

Record warmth almost every day

The Balearic Sea has been warmer than average on 270 of the first 271 days of the year, from January 1 through September 28. The only exception was March 4, when temperatures were slightly below average.

The sea also reached record temperatures on 24% of the days analysed in 2026. Looking at the most recent 100 days, the proportion rises to 44% of days reaching record levels.

Data from Spain’s State Ports buoy network also show that historical water-temperature records for October were set at several locations on October 1, according to data reviewed by Servimedia.

These included:

  • 26.6°C at the coastal buoy off Tarragona, with records dating back to 1992.
  • 26.37°C offshore from Cape Palos, with data available since 2006.
  • 26.36°C offshore from Tarragona, where records date back to 2004.
  • 25.8°C at the coastal buoy off Barcelona, with records dating back to 2004.
  • 24.85°C offshore from Cape Begur, where records have been collected since 2001.

The figures highlight just how unusually warm the western Mediterranean has become, including the waters surrounding the Balearic Islands, a major destination for visitors to Ibiza, Mallorca and the rest of the archipelago.

How Warmer Seas Can Intensify Torrential Rain

Del Campo explained that exceptionally warm seawater provides a major additional source of energy, encouraging the development of the intense storms responsible for the recent rainfall.

Warmer water also increases evaporation, meaning that more moisture can enter the atmosphere.

“Such warm waters provide an extraordinary supply of energy, favouring the formation of these very intense storms,” Del Campo said. “They also favour evaporation, making the air more humid.”

According to the Aemet spokesperson, these conditions can become particularly significant when combined with other geographical and atmospheric factors.

“This, together with factors such as winds blowing from the sea towards the land and the presence of mountains in areas close to the coast, leads to the formation of storm cells capable of producing large amounts of rainfall, even when atmospheric conditions do not initially appear particularly favourable.”

That combination is especially relevant along Spain’s Mediterranean coast, where warm sea temperatures, moist air and coastal mountain ranges can create the conditions for extremely intense rainfall.

Climate Change and the Future of Mediterranean Rainfall

Del Campo stressed that the relationship between unusually warm Mediterranean waters and extreme rainfall requires further investigation, but said the recent episode highlights a broader concern linked to human-driven climate change.

“This is therefore an issue that will need to be investigated in greater depth, but it shows how the warming of sea waters, driven by anthropogenic climate change, can make — and in fact does make — torrential rainfall events more severe.”

For the Balearic Islands and popular Mediterranean destinations such as Ibiza, increasingly warm sea temperatures are therefore an important part of the wider picture of how the region’s weather is evolving.

The latest rainfall episode demonstrates how unusually warm Mediterranean waters can contribute to the development of more intense and potentially more damaging rainfall events, particularly when they coincide with favourable wind patterns and the region’s complex coastal geography.