Andrea Innocenti The meteorological autumn of 2026 promises a mix of anomalous temperatures and heavy rainfall. According to the latest projections from the European Centre for Climate Change (ECMWF), September will bring some climatic surprises, with a marked contrast between periods of persistent heat and periods of atmospheric instability.
The Mediterranean, still loaded with the heat accumulated during the summer, will play a crucial role in this scenario.
Its waters, up to 5°C warmer than average, will act as a powerful heat accumulator, mitigating the autumnal cooling and maintaining high temperatures along the coasts and inland areas.
The first disturbances from Northern Europe
After a period of relative stability, projections indicate the arrival of new disturbances from Northern Europe starting in mid-September.
These cooler air masses will clash with the still-warm Mediterranean, creating ideal conditions for the development of intense thunderstorms and locally violent weather phenomena.
The first regions to be affected will be those in the North and the Tyrrhenian slopes, where showers and thunderstorms are expected accompanied by a sudden increase in winds.
The heaviest precipitation could be concentrated along the Apennine ridges and on exposed coastal areas, where the contrasts between the incoming cold air masses and the still warm sea surface would enhance the genesis of maritime storm systems.
The return of the anticyclone and the anomalous heat
Once the weather patterns have passed, the latest updates from the European Centre are beginning to hint at a return of the anticyclone after September 20th. Temperatures are expected to rise, with thermal anomalies likely to reach several degrees above what is expected. In short, it will be warmer than normal.
This period of anomalous warmth will be favored by the Mediterranean , which will gradually release the heat accumulated in previous months. Sea surface temperatures, still exceptionally warm, will keep temperatures high both along coastal and inland areas, extending an unusually warm period until early October.
The unknown of the next few months
Autumn is on the move. The extent of the unseasonal heat and the incredible energy stored in the Mediterranean represent the real unknowns of the coming months. The contrast between the first cool Atlantic breezes and such a warm sea will provide the ideal fuel for potentially intense storms and weather events.
Long-term projections indicate that temperatures will continue to remain above average, extending an unusually warm period that is set to accompany much of the Old Continent until the beginning of October.