Severe Weather Sweeps Europe September 16–19: Heavy Rain Moves From Spain to Italy and the Adriatic

A dangerous spell of severe weather is moving east across the Mediterranean. After torrential rain affected parts of Spain on Wednesday, September 16, the main storm zone shifted toward northern Italy and the Adriatic on Thursday, September 17. Orange-level warnings cover parts of Italy, Croatia and Slovenia, while Spain is still dealing with localized flood risk, thunderstorms and hail.

Spain: Wednesday–Thursday, from Mallorca to Murcia

AEMET issued a series of orange-level warnings across several regions. The event developed in waves: mainland Catalonia, Aragon and southern Mallorca were affected first; the warning area then expanded across Mallorca overnight; by Thursday morning, stronger storms and heavy rain had shifted toward Murcia, Almeria, Albacete and both northern and southern Alicante.

Italy and the Adriatic: Thursday, September 17

As the Spanish phase began to ease, the storm system shifted toward northern Italy and the Adriatic. Orange-level warnings covered multiple Italian regions on Thursday, September 17, while Croatia and Slovenia also faced elevated risk.

Official rainfall totals for Italy are published in greater detail by Protezione Civile and the Italian Air Force weather service. Meteoalarm confirms the warning level and hazard type across the broader European warning network.

Where the risk is highest

The most dangerous Spanish zones are the Barcelona coast and both northern and southern Alicante, where very heavy multi-hour rainfall may be compressed into only a few hours. That kind of short-duration intensity can overwhelm drainage systems and quickly flood roads, underpasses and normally dry channels.

In the Italian phase, Friuli Venezia Giulia stands out because its orange-warning window lasts almost two days. A long warning period does not automatically mean nonstop extreme rain, but it does indicate a prolonged period in which repeated thunderstorms and heavy rain may affect the region.

Why this is happening

The broader setup is being driven by an unstable air mass and an active upper-level trough moving east across the Mediterranean. The sequence began over the Iberian Peninsula and the Balearic Islands and then progressed toward the Alps, northern Italy and the Adriatic.

This type of autumn Mediterranean setup becomes more dangerous when cold air aloft interacts with a still-warm sea surface. The contrast increases instability and can fuel deep convection, intense thunderstorms and very high short-duration rainfall rates.

What happens next

In Spain, the most active phase is expected to ease during the second half of Thursday, September 17. In northern Italy and around the Adriatic, however, the main risk is still unfolding.

Most orange-warning windows in Italy run through Thursday night or early Friday, September 18. In Friuli Venezia Giulia, the elevated-risk period extends into the early hours of Saturday, September 19.

What residents and travelers should do

• Never drive across a flooded roadway.
• Avoid underground garages, underpasses and normally dry riverbeds during intense rain.
• Keep vehicles under cover where 2 cm hail is possible.
• In northern Italy and the Adriatic, follow local updates from Protezione Civile, DHMZ in Croatia and ARSO in Slovenia.
• Allow extra travel time during the main warning windows, especially overnight and early in the morning.

Sources