Polar air arriving from September 23: temperature drop in Northern Italy

A mass of polar air is expected over Italy starting from Wednesday, September 23, with more pronounced effects on the northern regions. The arrival of these cool currents, driven by a vast cold depression stationary over northeastern Europe, will cause a sharp drop in temperatures, especially in the North.

We will transition from typical late-summer values to decidedly cooler conditions, with lows that may drop significantly in Alpine valleys and plains. Maximum temperatures will also remain subdued during the central hours of the day, while northerly winds will make the air biting in exposed areas, giving the impression of a now firmly established autumn.

The weather event forecast for next week originates from a change in atmospheric circulation on a European scale. The triggering cause is the development and positioning of a "vast cold depression" over northeastern Europe. This low-pressure area, fueled by air from polar regions, acts as an engine that draws and pushes cold air masses southward.

The mechanism that brings cold air to Italy is called "stretching" of the depression, which promotes the descent of cool currents along its western edge, directing them toward the Mediterranean and the Italian Peninsula. This phenomenon is typical of seasonal change, when the thermal contrasts between the North Pole—which begins to cool rapidly—and lower latitudes become more pronounced. The main effect for Italy will be a sharp climatic divide: in the North, significant cooling with few intense rains, while in the South, the contrast between the incoming cool air and the warmer air present could trigger thunderstorms and increase the risk of local hydrogeological issues.