A disturbance in the stratospheric polar vortex affects Itália from this Thursday, November 27, 2025, with intense rain and strong winds forecast for the center and south of the country. The phenomenon, caused by the weakening of air currents in the Polo Norte, results in the descent of cold masses that alter the European climate pattern. Autoridades issued warnings in regions such as Toscana and Abruzzo, where rainfall could exceed 100 mm in 24 hours.
The event takes place between November 27th and 30th, with local peak times between 8am and 6pm, and extends to the beginning of December, according to meteorological models such as ECMWF and GFS.
- Main impacted regions: Toscana, Lácio, Campânia and Sicília.
- Types of phenomena: Chuvas torrential, snowfall at altitudes above 800 meters and wind gusts of up to 90 km/h.
- Main causes: Ondulações in the jet stream that fragments the vortex, allowing arctic inflows.
Experts monitor the development as the disturbance could prolong the peninsula’s early winter.
Causes of atmospheric disturbance
The weakening of the polar vortex begins in the stratosphere, where zonal winds decrease in speed from 10 hPa in altitude. The Essa configuration, observed since November 14, allows planetary waves, such as Wave 1, to move the cold core to mid-latitudes.
Models indicate that the phenomenon has gained strength in recent days, with positive thermal anomalies over Ártico contributing to the instability.
Immediate impacts on the center of Itália
Central regions face the peak of bad weather this Thursday, with rain concentrated in Florença and Roma. Volumes accumulated amounts reach 80 mm in urban areas, increasing the risk of flooding on expressways.
Southeast winds reach 70 km/h on the Adriatic coast, complicating maritime traffic in ports such as Ancona.
Protezione Civile activated emergency centers in 12 provinces, distributing alerts via official apps at 6am local time.
Temperatures drop to 5°C in Roma at dusk, with thermal sensation reduced by the winds.
Forecasts for the south and islands
In the south, Campânia has recorded isolated storms since the early hours of November 27, with lightning affecting electrical networks in Nápoles. Previsões points to 120 mm of rain until Saturday, November 29, in Salerno.
The eastern Sicília, including Catania, sees libeccio winds exceeding 80 km/h, with sea waves of 3 meters.
Light snowfall occurs in the Apeninos Calabrians above 1,000 meters, accumulating 10 cm in a few hours.
A partial truce arrives on Sunday, November 30, but with remnants of high humidity.
Alpine and northern regions under cold influence
In the north, the Arctic cold arrives without intense precipitation, but with night frosts in Milão and Turim. Mínimas of -2°C is recorded on the Padana plain at 4am local time on Friday.
The western Alpes forecast moderate snowfall at altitudes above 1,500 meters, with 20 cm at Courmayeur.
Lake Maggiore faces dense fog in the morning, reducing visibility to 500 meters on roads.
This cold phase persists until the end of the month, with maximum temperatures limited to 8°C in Veneza.
Prevention measures adopted
Local authorities recommend avoiding unnecessary travel in risk areas during peak hours, between 10am and 4pm.
- Preventive evacuations on vulnerable slopes in Toscana.
- Temporary closure of schools in municipalities with high rainfall in Lácio.
- Monitoring of dams on the river Tibre, with high levels since November 26th.
Health services prepare units for cases of hypothermia in exposed areas.
These actions are based on updated protocols from Protezione Civile, tested in similar 2024 events.
Expected evolution by December
The stratospheric disturbance is projected to last until December 5, with possible complete fragmentation of the polar vortex. Isso increases the chances of new cold fronts in the Mediterranean Europa, affecting air flows over Itália.
Ensemble models indicate a 60% probability of partial stabilization at the beginning of the month, but with remnants of instability.
In the long term, winter 2025-2026 could record anomalies, with averages 2°C below normal in January.
Factors such as the residual El Niño influence persistence, according to long-term analyses.
Regional differences in weather pattern
While the south deals with excessive humidity, the north experiences relative dryness, contrasting with annual precipitation averages. In 2025, Toscana accumulates 20% above the norm by November, worsening saturated soils.
Abruzzo sees moderate sirocco winds, transporting dust from Saara and reducing air quality in Pescara.
These variations highlight the complexity of the perturbed jet stream, which directs irregularly shaped flows.
Data from automatic stations confirm 15% deviations in wind patterns since the equinox.
Trends observed in recent years
Similar events occurred in 2023, when a vortex split brought early frosts to the peninsula. At the time, Milão recorded -5°C in mid-November, similar to today.
Records from 2024 show 15 days of severe weather warnings in the fall, a 10% increase compared to 2022.
Global warming accelerates these disturbances, with the frequency of polar crises rising by 25% in the decade.
European studies correlate these patterns with variations in the stratospheric ozone layer.
Itália records, on average, 8 high-intensity events per winter, with annual costs in billions of euros for recovery.
Preparing for the long winter
With the calendar pointing to December, forecasters are emphasizing the need for heating stocks in alpine homes.
- 30% increase in demands for electricity in the north due to consumption peaks.
- Vaccination campaigns against seasonal flu in cold regions, started on November 20th.
- Updates to road infrastructure to withstand frost on highways such as the A1.
These strategies aim to mitigate disruptions in supply chains, especially in Adriático ports.
Continuous monitoring via European satellites guarantees alerts 48 hours in advance.