Venice Tide Forecast: Acqua Alta This Week

Tide forecast for the coming days (updated Thursday 3 Sep)

Bulletin issued by the Comune di Venezia tide centre on Thursday 3 Sep at 10:30 (Comune di Venezia, 2026). Heights are in centimetres above the Punta della Salute datum, the reference used on every sign and siren in the city. The highest forecast peak in this bulletin is 70 cm at 14:55 on Thursday 3 Sep: no flooding expected.

Thursday 3 Sep: high 14:55 at 70 cm, low 22:40 at 10 cm. Outlook: no flooding expected.

Friday 4 Sep: high 04:35 at 30 cm, low 07:10 at 25 cm, high 15:10 at 60 cm. Outlook: no flooding expected.

Saturday 5 Sep: low 01:00 at 10 cm, high 18:00 at 55 cm. Outlook: no flooding expected.

Sunday 6 Sep: low 02:30 at 5 cm, high 10:10 at 50 cm, low 15:00 at 35 cm, high 20:05 at 55 cm. Outlook: no flooding expected.

Monday 7 Sep: low 03:20 at -10 cm, high 10:25 at 55 cm, low 15:50 at 25 cm, high 21:10 at 60 cm. Outlook: no flooding expected.

Forecasts beyond 48 hours can move by 20 cm or more as wind and pressure change; check again the day before you need it. The official bulletin, the tide graph and the siren codes are on the Comune's Centro Maree page linked below.

What each tide height means

The Comune publishes the share of the city's public ground that floods at each height, and the numbers explain why a forecast of 95 cm is a footnote while 120 cm is news. At 80 cm the lowest corners of Piazza San Marco, in front of the Basilica, begin to take water through the drains. At 100 cm the square floods and roughly 5% of streets are wet; the raised walkways (passerelle) are set out on the main routes. At 110 cm about 12% of the city is under water and the sirens sound. At 120 cm the figure rises to roughly a quarter of the city, and at 140 cm to more than half (Comune di Venezia, 2026).

Tides above 110 cm are counted as significant events. They were rare a century ago and are now common in autumn: the frequency of tides above 110 cm rose from about 4 per decade in the early twentieth century to 95 per decade in the 2010s (Lionello et al., 2021). The record is 194 cm on 4 November 1966; the second highest, 187 cm, was reached on 12 November 2019.

When the MOSE barrier is raised

MOSE is the system of 78 mobile gates across the three lagoon inlets, operational since October 2020. It is raised when the forecast peak exceeds the operational threshold, which the authorities have set at around 110 cm at Punta della Salute, and it takes about half an hour to close the inlets and several hours to reopen them (Lionello et al., 2021). When the gates are up, the water level inside the lagoon stops following the sea, so a forecast of 130 cm outside can mean 80 cm in the city.

The forecast on this page is the astronomical and meteorological forecast for the sea; it does not by itself say whether MOSE will be raised. The decision is announced by the Comune, usually the evening before, on the Centro Maree page and through the city's alert channels. When a closure is announced, expect the Piazza San Marco area to stay largely dry, and expect vaporetto lines that cross the inlets, such as those to the Lido, to be diverted or suspended for the duration.

What the sirens mean

Venice warns of significant tides with sirens mounted around the city, sounded about three hours before the predicted peak. A single prolonged tone announces the alert; it is followed by a sequence of rising notes whose number gives the expected height: one note for 110 cm, two for 120 cm, three for 130 cm and four for 140 cm or above (Comune di Venezia, 2026). Residents also receive the forecast by SMS and app, and hotels post the day's peak at reception.

If you hear the sirens, look at the number of notes, not the volume. One note means wet feet in Piazza San Marco and the low streets around Rialto for a couple of hours either side of the peak. Four notes means most of the city floods and it is worth staying put until the water drops.

What to do during acqua alta

High water is a few hours long, twice a day at most, and it is not dangerous; it is inconvenient. The water rises slowly to the forecast peak and then falls at the same pace, so a tide peaking at 14:00 means wet streets from roughly 12:00 to 16:00 in the lowest areas. The raised walkways appear on the main routes between the station, Rialto and San Marco; vaporetti keep running except at the highest levels, when some landing stages close.

The practical kit is a pair of waterproof overshoes, sold from stalls and shops for about 10 to 15 EUR the moment the tide comes in, or ordinary rubber boots. Shops and bars put steel barriers across their doors and carry on trading. Keep to the walkways, avoid stepping into water you cannot see the bottom of (drains are open), and expect the Basilica and the museums around Piazza San Marco to delay opening until the square drains. Everywhere above 110 cm on the pavement height maps, which means most of Cannaregio, Castello and Dorsoduro, life goes on as normal.

When acqua alta is most likely

Significant tides cluster between October and January, when sirocco winds from the south-east push Adriatic water into the northern basin and low-pressure systems lift the sea surface. November has produced most of the record events, including 1966 and 2019. From April to August tides above 110 cm are rare (Lionello et al., 2021).

The astronomical tide sets the baseline: peaks are highest around the new and full moon, when spring tides add up to about 50 cm to the mean level. The forecast on this page combines that predictable component with the weather forecast for wind and pressure, which is why it is reliable for two days and indicative beyond that.