Data from the Socib coastal observation system in the Balearics indicate that the average temperature of the surface of the Balearic Sea on Monday (August 8) was 27.66 degrees, at least two degrees higher than the average for this day over the past forty years.
On July 18, the average temperature was 27.58 degrees, which was 2.98 degrees higher than the 40-year average. Socib points out that these are "huge anomalies that coincide with atmospheric heat waves". A single heat wave can have limited effects, but if they happen often, the impact on the marine ecosystem will be negative. The highest daily average temperature recorded in the Balearic Sea by Socib was 29.1C on August 10, 2003; that was a particularly hot summer.
The buoy at Dragonera has been registering an average temperature of 28.55 degrees this month. Marine heat waves are defined as occurring when temperature is higher than usual for at least five consecutive days, something that has been happening this summer.