Climate, acqua alta and air in Venice

Seasons and winds

Venice has a humid coastal-plain climate: cold winters with frequent fog over the lagoon and the mainland, occasional frost and rare snow; hot, muggy summers, with high humidity that makes July and August heavy in the narrow calli, and evening thunderstorms. Winds matter: the bora, cold from the north-east, brings clear skies and lowers the tide; the scirocco, warm and humid from the south-east, pushes water into the lagoon and, with low pressure, causes the most serious high tides.

Spring and autumn are the best seasons, but autumn is also the one with the highest tides. Those living on the ground floor in the historic centre must reckon with rising damp and, in the lowest areas (San Marco first), periodic flooding.

Acqua alta and the MOSE

Acqua alta is the exceptional tide that floods the lowest parts of the city, mostly between October and January. The municipal Centro Previsioni e Segnalazioni Maree publishes multi-day forecasts, the bulletin, real-time data and warnings: alerts come through the city sirens (rising tones for rising levels), the «Centro Maree Avvisa» Telegram channel and the website; the municipality lays raised walkways along the main routes. Anyone moving here should subscribe to the channel and know the height of their ground floor.

Since October 2020 the MOSE has been operational, the system of mobile barriers at the three lagoon inlets (Lido, Malamocco, Chioggia) run by the Consorzio Venezia Nuova: it is raised when the forecast exceeds the operating threshold set by the authorities and has spared the city the highest tides, while the lowest areas can still get wet with medium tides. The MOSE does not remove the problem of rising mean sea level.

Air quality

Venice lies in the Po basin and shares its air: the Mestre station and those in the historic centre record many days above the daily PM10 limit every year, concentrated in winter, placing the municipality among the most critical Italian provincial capitals in SNPA reports; heating, mainland traffic, the industrial zone and the port (ships and yard vehicles) all weigh. ARPA Veneto publishes daily data and the Region applies seasonal anti-smog measures in the plain's municipalities.