Acqua alta in Venice is the high tide that floods parts of the historic centre, and it happens mostly between October and December, with November the peak month. The city counts a tide as acqua alta when it passes 110 cm above the Punta della Salute reference level; at that height about 12% of the city is under water for a few hours. Since autumn 2024 the MOSE barriers are raised to keep the tide in the city below 110 cm, so the big floods are now rarer, but the lowest areas, starting with Piazza San Marco, can still get wet at 80-100 cm.
This guide explains when it happens, what each tide level means on the ground, and what to do if a high tide is forecast during your stay. Figures come from the City of Venice, its Tide Centre and ISPRA, the national environmental agency, checked on 30 October 2026.
When is acqua alta in Venice?
High tides can happen in any month, but they cluster in autumn and early winter. The city's Tide Centre (Centro Previsioni e Segnalazioni Maree) says that November has the most tides of 110 cm or more, followed by December and October, and that those three months together account for about 70% of the events. Summer high tides are very rare. Late winter can still bring episodes: between 28 January and 6 February 2026, as reported with the head of the city's Tide Centre, tide levels stayed above 100 cm for about 41 hours, against just over four hours in the same period a year earlier.
Within a single day, acqua alta follows the tide. The water rises for a few hours around the peak and then recedes. A tide of 120 cm lasts on average less than an hour and a half above that level, according to the city.
How often does acqua alta happen?
More often than it used to. ISPRA reports that tides of 110 cm or more went from fewer than two a year in the 1950s to more than ten a year in recent years, with a record 28 in 2019. One reason is that the relative mean sea level in Venice has risen by about 20 cm since the 1950s, because the sea is higher and the ground has sunk. The worst recent event was on 12 November 2019, when the tide reached 189 cm, second only to the flood of November 1966.
Since the MOSE barriers came into use in 2020, many of these tides are stopped at the lagoon inlets and never reach the city at full height. What visitors see today is mostly the smaller flooding of the lowest squares and quaysides.
What do the tide levels mean on the ground?
Forecasts are given in centimetres above the 1897 reference level at Punta della Salute. This table translates them into what you will see, using the City of Venice's own thresholds.
| Forecast tide | What it means in the city |
|---|---|
| Above 82 cm | Water becomes noticeable in Piazza San Marco, the lowest point of the centre. |
| 95 cm | Some water bus (vaporetto) routes may be changed; services keep running. |
| 105 cm | Flooding begins around the Rialto Bridge. |
| 110 cm | Official acqua alta: about 12% of the city floods for a few hours. MOSE is normally raised before this level is reached. |
| Up to 120 cm | The main pedestrian routes stay usable, partly on raised walkways (passerelle). |
| 135 cm | Water reaches walking level in the square in front of the railway station. |
| Over 140 cm | Exceptional tide: about 59% of the historic centre floods, with up to about 60 cm of water in Piazza San Marco. |
Most acqua alta days involve only a few centimetres of water in the lowest areas. A pair of rubber boots is usually enough, as the city's tourism site puts it.
What causes acqua alta?
Acqua alta is the sum of the normal astronomical tide, driven by the moon and the sun, and the weather. A strong sirocco wind from the south-east pushes water up the Adriatic towards Venice, and low air pressure lets the sea rise further. When a storm surge arrives at the same time as a high astronomical tide, the water in the lagoon goes above the lowest pavements. That is why the Tide Centre's forecast can change within hours: it depends on the wind as much as on the calendar.
Does MOSE stop acqua alta, and when is it raised?
MOSE is a system of 78 mobile gates at the three inlets that connect the lagoon to the sea: Lido, Malamocco and Chioggia. When a high tide is forecast, the gates rise from the seabed and close the lagoon until the peak has passed. The 100th raising took place on 12 March 2025, and the Ministry of Infrastructure and Transport estimates that MOSE avoided more than €2.6 billion in damage in its first five years.
The trigger has been lowered over time: the barriers went up for forecasts of 130 cm until 2023, then 120 cm, and since autumn 2024 the aim is to keep the tide in the city below 110 cm. In practice, as reported in February 2026 with the head of the city's Tide Centre, the gates are raised when the forecast for the city reaches 101 cm or more, to leave a margin for error. Each raising costs around €200,000.
So MOSE stops the big floods, but not the small ones. Between roughly 80 and 100 cm the barriers usually stay down, and Piazza San Marco and the waterfront can still flood. If you want to see acqua alta, this is the version you are most likely to meet.
Is there acqua alta in Venice now?
Check the forecast rather than the news. The City of Venice's Tide Centre publishes the real-time level and forecasts for the current day and the next two on the city's website and social channels. The free hi!tide Venice app uses the Tide Centre's data and shows which parts of the city are dry or flooded, including the levels at the main water bus stops. On high-water days an acoustic alert sounds in the historic centre and on the islands before the peak, signalling the expected height.
What should you do if acqua alta is forecast?
- Check the peak time. Flooding usually lasts a couple of hours around the peak. Plan museums, churches or a long lunch for those hours and walk before or after.
- Pack boots. Rubber boots are enough for most tides. Leave suede and canvas shoes at the hotel.
- Use the raised walkways. Passerelle on the main routes keep them usable up to about 120 cm. Expect them to be busy around the peak.
- Watch your step. The edges of canals and quaysides disappear under the water. Stay on routes you can see and do not cut across open squares near the water's edge.
- Allow extra time for water buses. Services keep running, but some routes change when the tide is high.
- Choose your base. If you travel in November or December and want to avoid wet feet, a hotel away from the lowest areas around San Marco is easier. Our Top Hotels in Venice list shows each hotel's area.
Should you cancel or change your trip because of acqua alta?
Usually not. Most episodes last a few hours and affect a small part of the city, and since MOSE the floods above 110 cm rarely reach the streets. The city's tourism portal states that access to the whole city is guaranteed even on high-water days. If you pack boots and check the forecast each morning, a November visit works well. For neighbourhoods, transport and food, see our Venice City Guide, or plan the art and the dinners with Venice in 48 hours. Thinking of staying for a season? Living in Venice covers the practical side of daily life in the city.
FAQ
What month is acqua alta in Venice?
November has the most high tides, followed by December and October. Together they account for about 70% of tides of 110 cm or more. Summer high tides are very rare.
How long does acqua alta last?
Usually a couple of hours around the peak of the tide. A 120 cm tide stays above that level for less than an hour and a half on average.
Does MOSE stop acqua alta?
It stops the high floods. The barriers are raised to keep the tide in the city below 110 cm, but lower tides of 80-100 cm can still flood Piazza San Marco.
Where can I check the acqua alta forecast?
On the City of Venice Tide Centre's website and social channels, or in the free hi!tide Venice app, which uses the Tide Centre's data.
Is it safe to visit Venice during acqua alta?
Yes, with care. The main routes stay open, raised walkways are set up, and rubber boots are usually enough. Avoid the edges of canals and quays, which are hidden under the water.
Sources (checked on 30 October 2026): City of Venice tourism portal: High water, Comune di Venezia: Venice and high water, Comune di Venezia, Tide Centre: seasonality of the tide, Comune di Venezia, Tide Centre: the meteorological contribution, ISPRA: one year after the exceptional high water of 12 November 2019, MOSE Venezia (Consorzio Venezia Nuova), ANSA: MOSE's 100th raising, citing the Ministry of Infrastructure, Il Post: MOSE threshold lowered to 110 cm (September 2024), Il Post: MOSE in early 2026, with the head of the Tide Centre and hi!tide Venice on the App Store.
Photo credits: cover by Egor Gordeev and St Mark's waterfront by Anna Hunko, both via Unsplash.
