In 2026, a major marine heatwave has developed over the Mediterranean Sea, with surface temperatures reaching 28°C or higher across much of the region. In some areas, such as near the Balearic Islands, temperatures climbed as high as 32-33°C—5 to 6 degrees warmer than the historical average. This unusual warmth has persisted for several weeks and is expected to continue, with the potential for a new heatwave to affect southeastern France. In that region, temperatures are projected to reach 30°C or higher across areas south of the Loire River, with some parts of the Languedoc-Roussillon region possibly experiencing temperatures of 37-39°C. In certain locations, temperatures could even peak at 40°C or 41°C, which would be exceptionally high for the region. The elevated sea temperatures are a significant driver of severe weather events in the Mediterranean. Warm waters provide the energy needed for the formation of intense weather phenomena such as Cévenol episodes—localized heavy rainstorms in the Cévennes mountain region—Mediterranean episodes, which are broader rainstorms affecting the southeastern plains and coasts, and medicanes, which are tropical-like cyclones capable of producing strong winds and heavy rainfall. Additionally, derechos—long lines of violent thunderstorms that can travel hundreds of kilometers—can be intensified by these conditions. This heatwave has been linked to some of the most severe weather events in recent years. For example, the 2022 derecho event, which swept from Corsica to the Czech Republic and recorded wind speeds of up to 225 km/h in Marignana, Corsica, was influenced by warm sea temperatures. Similarly, the 2024 floods in Valencia, which brought over 500 mm of rain and caused more than 200 fatalities, were also affected by the higher-than-normal sea temperatures that contributed to intense rainfall. While the marine heatwave increases the likelihood of severe weather by boosting evaporation and creating conditions for heavy rainfall and flooding, the actual occurrence of a disaster depends on a complex mix of factors, including atmospheric patterns, urban development, natural geography, and the precise location of intense weather systems. As a result, experts are urging close monitoring of the Mediterranean region during the autumn of 2026, as the conditions are favorable for the development of strong depressions and thunderstorms.