Faro, Portugal, July 9, 2026 (Lusa) - The Portuguese Navy said on Thursday that it had recorded two marine heatwaves off the coast of Faro, one moderate and one severe, with sea surface temperatures reaching 26.1°C.

According to a Navy statement, the two episodes were identified at the Faro Costeira buoy, which forms part of the Hydrographic Institute’s (MONIZEE) national coastal monitoring network, with an average daily sea surface temperature of around 25°C recorded between 15 June and 9 July.

Marine heatwaves are defined as periods of at least five consecutive days during which the sea surface temperature remains significantly above the usual values for the season and the region.

These phenomena can affect marine ecosystems, fisheries and aquaculture, and have become more frequent and intense due to global warming.

The Navy classified the first marine heatwave as moderate, as it reached a daily maximum of 23.3°C, around 1.5°C above the 90th percentile threshold for that date.

The second, however, was classified as strong, with a daily maximum of 24.8°C, approximately 2.2°C above the same threshold.

Although the classification of these phenomena depends on the persistence of high temperatures, the Navy points out that the buoy recorded an instantaneous maximum of 26.1°C during the period analysed, underscoring the magnitude of the observed warming.

The monitoring carried out by the MONIZEE network enables tracking of changes in sea surface temperature in near real time, contributing to the characterisation of extreme events in the Portuguese coastal ocean, the statement reads.

The Portuguese Navy concludes that the information gathered is considered “relevant for environmental monitoring, for understanding the thermal variability of the ocean, and for supporting activities that depend on sea conditions”.

JPC/ADB // ADB.

Lusa