Fine summer: disturbance brings instability and widespread thunderstorms to Italy

An Atlantic disturbance has been affecting Italy since September 18th, bringing generally unstable atmospheric conditions to much of the country. The weather situation is characterized by alternating clouds and sun with a risk of rain, showers, and thunderstorms, particularly likely in the Central-North, but also over Campania, inland areas between Basilicata and Puglia, Sicily, and eastern Sardinia. Locally intense phenomena are not excluded, potentially requiring weather alerts.

Maximum temperatures have dropped drastically in the North, while they are rising in the Center and stable elsewhere. In the evening, precipitation will tend to taper off, concentrating in the central and upper Adriatic sectors. For Saturday, September 19th, a return of fair weather is expected in the North, while unstable conditions with a risk of rain and thunderstorms in inland and Apennine areas will persist in the Center-South, Sardinia, and Sicily.

The unstable weather affecting Italy since September 18, 2026, is caused by the passage of the second Atlantic disturbance of the month, which is moving toward the Balkans. This phenomenon marks a clear seasonal transition from the summer phase to autumn conditions, with the arrival of unstable currents from higher latitudes that are altering the Italian meteorological picture.

International forecasting models, such as ECMWF and GFS, have been indicating this significant transformation for days. The disturbance, formed in the Atlantic, began its journey toward the Mediterranean, bringing colder and more unstable air. This weather system affects not only Italy but also the Balkans, where the cold intrusion will be particularly intense at the beginning of next week.

The seasonal transition requires special attention for agricultural activities and the maintenance of outdoor equipment, as sudden changes in atmospheric conditions can have significant impacts. Meteorologists emphasize that this is the first true cold air intrusion of the season, heralding the arrival of autumn with a progressive temperature drop across several Italian regions.