At ten in the morning on August 17, about 30 meters deep and near the island of San Andrés, in the waters of the Cabo de Gata park, the sea temperature was around 30 degrees. Something never seen by the most veteran diving instructors of the Levante Almeriense, who have spent much of this summer of 2026 diving in swimsuits and without neoprene, as if the Mediterranean were the Caribbean. The meteorological summer that ended yesterday — which spans from June 1 to August 31 — has been record-breaking both on land and at sea. And one of the effects it has left is a remarkable increase in the number of premature deaths associated with extreme temperatures.
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The Daily Mortality Monitoring System (MoMo), of the Carlos III Health Institute and the Ministry of Health, estimates that 5,111 people died in Spain as a result of heat during the three months of meteorological summer: 937 in June, 2,025 in July, and 2,149 in August. If we add to these figures the 123 deaths in May, when an early episode of extreme heat occurred, the number for this summer period recorded by Health reaches 5,234.
It is the highest figure since these data have been published, in 2015. The previous summer with the highest mortality due to high temperatures was 2022, when the estimate rose to 4,789 deaths.
These figures are not a count of people who die from heat. It is an estimate derived from crossing death data from the Civil Registry with the thresholds at which Health calculates temperatures are most dangerous for health. From the excess mortality — the number of deaths exceeding what was expected — an algorithm is applied to determine which were triggered by heat.
It is not, therefore, heat strokes, those sudden phenomena that cause the death of people exposed to the sun in broad daylight, usually due to work or sport, and which number a few dozen each year. It is a more subtle phenomenon, which does not appear on death certificates: heat undermines the health of vulnerable people, generally with pre-existing illnesses, and triggers processes that can end their lives when several days of very high temperatures occur. That is why almost all the deaths (97%) from high temperatures estimated by MoMo were over 65 years old. And more than half (6 out of 10) were over 85 years old.
Other systems, such as the MACE application, raise the number of heat-related deaths above 17,000. This discrepancy is because MoMo uses only extreme temperature thresholds for its calculation, while MACE’s is broader and includes all who died from heat.
The hottest summer
The State Meteorological Agency (Aemet) is already preparing its monthly and seasonal report, which will be published in the coming days, once all data are consolidated. But what has been recorded during these three months points to a year with abnormal heat. So much so that last week Aemet already announced that “it is practically certain that it will be the warmest in the historical series in peninsular Spain.” That series starts in the 1960s.
According to this public agency, the daily average temperature of the season has been 2.5 degrees above normal, taking as a reference the period between 1991 and 2020. The previous warmest summer recorded so far was last year’s, and the third was 2022. This concentration of records in this decade is an indicator of climate change, which makes records barely last a moment.
Furthermore, climate change increases extreme weather events, such as heat waves, which are becoming more frequent and intense. Of the 78 heat waves recorded by Aemet in peninsular Spain in the last 50 years, 31 (40%) have occurred between 2015 and 2025. In addition, they have grown in intensity and duration: in the last decade, each wave lasted on average 7.2 days, compared to 5 days in the previous 40 years. That is, they now last 30% longer in Spain.
The record-breaking summer of 2026 was greatly contributed to by sustained high temperatures in both June and July. During these two months, four heat waves occurred in peninsular Spain. The first began on June 21 and lasted four days. The second was recorded between July 5 and 9, and the third between July 21 and 23. The fourth started on July 29 and is expected to extend until August 1.
These extreme episodes have also helped set the stage for a disastrous fire season. Between July 1 and August 26, according to data from the European Copernicus system, nearly 250,000 hectares were affected by fires in Spain. And at sea, this sustained heat during June and July led to another incredible record: at the sa Dragonera buoy, off Mallorca (Balearic Islands), 33.02 degrees Celsius was recorded at four in the afternoon, the highest sea temperature recorded in Spain so far in the State Ports control system. The previous record dated from August 2024 and was more than one degree lower.
Spain has not been an isolated case, as much of Western Europe has also experienced a scorching summer, which has driven up deaths. In Germany, for example, 9,600 heat-related deaths occurred during the heat wave recorded between June 22 and 28. In France, 5,764 deaths were recorded between June 17 and 30.
