Rome – Italy is preparing for a radical change in weather. After days dominated by the Saharan anticyclone, which maintained summer-like temperatures and clear skies across much of the country, starting Monday, September 22, the atmosphere will once again become unstable. Projections from the European meteorological model ECMWF, confirmed by experts at Meteored Italia, indicate the arrival of a strong Atlantic low, coinciding precisely with the autumnal equinox.
The return of the jet stream
The weather dynamics are linked to the polar jet stream, which, after weeks of linear flow, will once again exhibit marked undulations. The oscillation of the jet stream will initially point toward the Iberian Peninsula and then bend toward France and Italy, paving the way for an unstable air mass capable of fueling widespread rain and thunderstorms.
The regions most at risk
Meteorologist Daniele Ingemi explains that "between September 22nd and 24th, Italy will be hit by a wave of bad weather with showers and thunderstorms, some of which could be severe."
In the North, rainfall could exceed 50 millimeters in a few hours and reach 100 millimeters in 24 hours, especially in Lombardy, Veneto, Emilia-Romagna, and Friuli Venezia Giulia, with particular attention to the foothills.
The worsening weather will not spare central Italy: Tuscany, Umbria, Marche, and Lazio will see rain and thunderstorms, with the Tyrrhenian Sea exposed to self-regenerating phenomena caused by the Sirocco wind. Major cities are also likely to experience critical situations: Rome, Florence, and Naples are among the most at risk from flooding.
In the South, the low pressure system will particularly affect Campania, Tyrrhenian Basilicata, and Calabria, while in the hours leading up to the front, the climate will be made more oppressive by an increase in heat.
Towards an unstable October
Experts emphasize that this disturbance could mark the beginning of a more dynamic and unstable phase. "With the breakthrough of the Atlantic front," explains Ingemi, "Italy risks being hit more frequently by oceanic disturbances."
As early as mid-October, a succession of disturbed fronts and brief anticyclonic pauses is expected. The return of La Niña, altering the polar jet stream, will favor rapid and localized severe weather episodes, with potential for extreme events.
