Mediterranean Sea 1.8°C warmer than average in early October

The Mediterranean Sea was 1.8°C warmer than the climatic average during the first half of October, according to data from the Catalan Meteorological Service (Meteocat).

The data was collected by Josep Pascual, a meteorological observer in L'Estartit (Costa Brava) and a Meteocat collaborator through the Meteorological Observers Network (XOM).

On October 8, surface temperatures reached 21.7°C – 1.8°C above the 1998–2022 average. This continues a trend observed from June to September, particularly in June and July, with record-breaking surface temperatures not seen since measurements began in 1974.

For instance, on July 18, surface temperatures climbed to 26.8°C, around four degrees above the average and surpassing the previous record of 26°C set on July 23, 2023.

Marc Prohom, Meteocat's head of climatology, said that high surface temperatures have been recorded nearly every month during 2025, contributing to the formation of extreme weather events.

The summer of 2025 was the second warmest on record and caused significant thermal expansion of seawater in the western Mediterranean.

Meteocat's annual Climate Indicators Bulletin (BAIC) estimates that the average level of the Mediterranean has risen between 10 and 11 centimeters since the 1990s.