Marine heatwave Bulletin
Forecasts for 17 January 2026 ​

Key Takeaways

  • North Atlantic – the marine heatwave affecting the Bay of Biscay, the area bewteen Iceland and the British Isles, as well as the North Sea and the Baltic Sea, is decreasing in extent and remains stable in intensity. 
  • South Pacific – the marine heatwave around New Zealand  is expanding towards the east of the basin but is reducing in the south region.
  • Southern Ocean – with stable extent, the intensity of the marine heatwave between 30°E and 120°E is decreasing from strong to moderate categories.
Waves

Marine heatwave categories

European Zone

 

Mediterranean Sea

The marine heatwave affecting the entire basin decreases in extent and remains stable in terms of intensity, with moderate and strong categories still in place. 

North Atlantic

The area covered by marine heatwaves in the Bay of Biscay, between Iceland and the British Isles, as well as in the North Sea and the Baltic Sea, is decreasing in extent, but their intensity remains stable, with moderate and strong categories still occurring.

 

Global Ocean

North Atlantic

The marine heatwaves present in the Gulf of Mexico and the Caribbean Sea, decrease in extent and remain stable in terms of intensity, with moderate and strong categories still in place. The marine heatwave extending from the Antilles as far as the center of the basin is stable in intensity and area with moderate and strong categories. 

South Atlantic

The extent and intensity of the marine heatwave between 30°S and 15°S are decreasing to reach mainly moderate category

North Pacific

The marine heatwave in the center of the basin around 180°W and 50°N remains stable in terms of intensity, with moderate and strong categories still in place. Its extent decreases. Marine heatwaves around the Philippines and Indonesia, as well as those in the center of the basin extending to the North American coast, decrease in terms of surface area and intensity, with moderate and strong categories still in effect. 

South Pacific

The extent and intensity of the marine heatwave along the coast of Chile are decreasing, with less area affected by strong categories and still moderate categories. The marine heatwave around 100°W decreases in area and intensity, going from mainly strong and locally moderate and severe categories to mainly moderate and locally strong categories. The marine heatwave zones around New Zealand are expanding toward the east of the basin but is reducing in the south. The intensity increases with the development of strong and locally severe categories. Around Papua-New-Guinea, the extent of the marine heatwaves decreases, with only a few areas in moderate category.

Southern Ocean

The intensity of the marine heatwave between 30°E and 120°E is decreasing from strong to moderate categories. Its extent remains stable.

 

Weekly temperature anomalies

 

Sea surface temperature mean anomalies for the week 11 to 17 January 2026

Mediterranean Sea 0 °C to 2.5°C 
North Atlantic <-3 °C to >3°C 
South Atlantic <-3°C to >3°C 
North Pacific <-3°C to >3°C 
South Pacific -2°C to >3°C  
Southern Ocean -0.5°C to 2.5°C 

Forecasts for 17 January 2026

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NOTES

Datasets and products: Global Ocean Physics Analysis and Forecast (sea surface temperature) E.U. Copernicus Marine Service/ Mercator Ocean International. https://doi.org/10.48670/moi-00016