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Acqua Alta High Tide Flood Forecast in Venice

Aqua Alta with a Venice policeman for the Pedestrian Traffic
Aqua Alta Policemand Pedestrian Traffic
MO.S.E plan
On October 3, 2020, with real bad weather conditions and a high tide expected at 135 centimetres, as an emergency procedure the MO.S.E plan has been activated.

The 78 floating seawalls on about 1600 metres have been closed up and Venice remained fully dry while the hide tide time. It was a full success.

As the MO.S.E system is due to be in service only at the end of December 2021, it cannot be used until then for any high tide. But it has been decided to use it for all future high tides over 130 centimetres.

November 1966
Imagine Venice immersed at 100 % by two metres of water!

This time everybody was very afraid, the end of Venice! Venice sank and at the same time the poetry of Lord Byron:
“Ode on Venice” once again surfaced:

Oh Venice! Venice! when thy marble walls
Are level with the waters, there shall be
A cry of nations o'er thy sunken halls,
A loud lament along the sweeping sea!
If I, a northern wanderer, weep for thee”
Lord Byron

But truly, Acqua Alta has nothing to do with “the sinking” of Venice, which certainly is true but of less than a millimetre a year.

High Tide Acqua Alta in Venice - Venice flooding forecast

As for the weather, high tides forecast is quite difficult. As a result high tide, Acqua Alta forecast can be at maximum for 4 or 6 days in advance, and it can even change in the last hours.

Venice Flood Acqua Alta Forecast

Alarm Sirens in case of Acqua Alta High Tide in Venice:

An initial alert signal will be followed by:
Level 1.10 metres: One long sound.
Level 1.20 metres: Two crescendo sounds.
Level 1.30 metres: Three crescendo sounds.
Level 1.40 metres: Four crescendo sounds.

Listen the High Tide Acqua Alta Alarm Sirens Signals

To listen these high tide signals, please click on the following links:
Initial alert signal
Signal level 1.10 metres
Signal level 1.20 metres
Signal level 1.30 metres
Signal level 1.40 metres

Warning Codes in case of High Tide (Acqua Alta) in Venice

Tide between 0.8 metres and 1.10 metres High Level Warning Code Yellow
Tide between 1.10 metres and 1.40 metres Very High Level Warning Code Orange
Tide level over 1.40 metres Exceptional Level Warning Code Red

Venice under water: Town Surface percentage

Percentage of Venice that will be under water for different tide levels.

Warning "Under water" begins at one centimetre of water covering the ground, meaning that in the following table, some parts of Venice can be under 10 centimetres of water while for others it will just be a paddle like after the rain!

Interactive Venice map with levels. Click on the + arrow on the map to enlarge and know the levels for each street (in centimetres)

Percentage of the whole Venice Surface under water depending on the tide level:

1 metre: 3,56 % of Venice is under water
1.10 metres: 11,74 % of Venice is under water
1.20 metres: 35,18 % of Venice is under water
1.30 metres: 68,75 % of Venice is under water
1.40 metres: 90,19 % of Venice is under water
1.50 metres: 96,33 % of Venice is under water
1.60 metres: 99,27 % of Venice is under water
1.70 metres: 99,74 % of Venice is under water
1.80 metres: 99,86 % of Venice is under water

Acqua Alta Saint-Mark Square Venice Italy
Acqua Alta Saint-Mark Square Venice
Certainly, over last century, Venice sank about 10 centimetres, due to industrial groundwater extraction but largely stopped when artesian wells on the mainland were capped in the 1960s.

Acqua Alta, what is it?

Then it is what?

Acqua Alta occurs when certain events coincide; the high tide forms an alliance with low pressures and that their windy friend, Sirocco, participates with our friend the Moon.

These elements together trigger the across-the-board flood of waters of the lagoon in Venice.

Igor Stravinsky Venice Italy 1925
Igor Stravinsky in Venice in 1925

When Acqua Alta plays the Music

History is true and arrived at Igor Stravinsky the Acqua Alta had been then so high as the compositor could no longer return to his hotel.

The concierge of aforementioned hotel Bauer, took Igor Stravinsky in his arms and carried him indoors.

It was after this Acqua Alta that Igor Stravinsky writes “The Flood”!

Our Advises Living well with Acqua Alta

The biggest problems Acqua Alta poses, at most some centimetres of water in calli (streets) which gives them a glistening aspect, is getting the camera quickly!

Besides, you will be warned in case of serious Acqua Alta. Sirens (which still date to the last world war), will shout a warning signal. If you are surprised in the city without Wellington boots, the dealers will be delighted to give you plastic bags for makeshift boots to make waiting better!

The period at risk is from September 15th till April 15th every year.

Venice Flood Acqua Alta Forecast

If you think to visit at this time of the year, it is best to be prepared with a pair of Wellington boots and enjoy the pleasure, as the children, of walking in the puddles!

MO.S.E plan

It is a big “Pharaonic” plan of the installation of seawalls to try to check the phenomena of Acqua Alta by installing in the entries of the lagoon (in the channels of Lido, Malamocco and Chiogga) 78 floating seawalls on about 1600 metres and divided in four chunks with huge hatches that can close up or open according to the whims of the tide.

The estimated cost is of 5,5 thousand million euro more about 35 million euro of expense of annual maintenance. It should be done by the end of year 2021.

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