Mediterranean and North Atlantic show signs of relief from marine heatwaves
The data is clear: according to the latest ocean temperature bulletin published by Mercator Ocean International, operator of the EU’s Copernicus Marine Service, August 2025 ranked as the third-warmest August on record globally in terms of Sea Surface Temperatures (SST).
The report analyzes ocean temperature trends, changes, and updates at both global and regional levels, providing crucial information to the scientific, environmental, and climate monitoring communities worldwide.
77% of the Mediterranean Sea recorded above-average SSTs. However, unlike June and July, most of the basin remained near normal, with only 8% of the area showing SSTs more than 1°C above the long-term average (compared to 67% and 64% in June and July, respectively).
As for marine heatwaves in the Mediterranean, August brought some relief. The affected area increased from 8% to 16% of the basin, peaking at 29% in mid-August. Nevertheless, August 2025 was not considered an extreme month for marine heatwaves, with events remaining localized and mostly moderate in intensity, especially when compared to recent years.
The Copernicus Marine Service is dedicated to ocean observation, monitoring, and forecasting. It is funded by the European Commission and implemented by Mercator Ocean International.
It provides regular and systematic reference information on the physical and biogeochemical state of the ocean at both global and European regional scales.
Mercator Ocean’s marine heatwave bulletins are based on data provided by the Copernicus Marine Service.