Sea temperature in Portugal's Algarve reaches record highs as 'marine heatwave' hits

Portugal's southern Algarve region experienced a "marine heatwave", the country's Maritime Authority said on Tuesday, after collating the results recorded by a buoy placed in the sea near Faro's beaches between 28 June and 9 July.

The buoy is part of the Hydrographic Institute's national monitoring network (MONIZEE).

According to the data, the waters around the beaches in the area reached temperatures of up to 25.1°C.

Temperatures are "significantly higher" than the average of the last 20 years, indicating the occurrence of an extreme phenomenon called a "marine heatwave", according to a statement published on the Portuguese Navy's website.

"A 'marine heatwave' is considered to occur if the daily sea temperature exceeds, for at least five consecutive days, a high statistical limit, called the 90th percentile of the average temperature for that region and time of year," the statement said.

According to the statement, the daily seawater temperature recorded in Faro "exceeded the average temperature by more than 5°C" and therefore corresponds to "the category of marine heatwave considered extreme".

"The average temperature was determined from records collected in Faro over the last 20 years (2004-2024), serving as a reference for identifying marine heatwave events."

Since the data was collected, temperatures have returned to normal with the sea in the Algarve now cooler, with the water between 18 and 20°C.