About Those Sirens -Handy Info for High Water in Venice

The new season of “acqua alta” – high tides and high water has just begun in Venice. This morning the level was at 110cm. That means that Piazza San Marco has enough water for a good wading. It looks like there will be acqua alta throughout the next week. In advance of unusually high tides, Venice has a system of sounds – sirens which will advise you as to 1)how high exactly they expect the tides 2)and how soon.

So in case you are traveling to Venice this week or just to store in the back of your mind, here is the information issued by Venice. Not all areas flood, some have been refurbished to raise the height of the fondamente, but flooding doesn’t always arrive as a result of wave action or sheer height of the lagoon. The very porous underpinnings of Venice allow the water to seep up through the grates and between the ancient Ischia stones.

Piazza San Marco- last year

Like the rest of the world, there are color codes, yes even for high water or the lack thereof. All measurements are in cm and the designation represents the cm above nominal sea level. Remember that Piazza San Marco is at 95cm and from that you can judge everything and that when we hit orange, life gets tough for locals, store owners and anyone trying to go by vaporetto or foot. If it hits Red (rosso) it a disaster for the city.

color table

Like you get your weather report on a daily basis, the level of the sea is part of Venetian’s daily report. Here is the report of Saturday forcasting for the week. The notable thing on this chart is that on 13 November, the low doesn’t get all the water out of the lagoon which could lead to a larger flooding later should the winds change direction.


Now about those sirens.

Since 1968, alerting in case of high water occurs through sound warnings launched by powerful sirens. These will wake you from your deepest sleep and sound a lot like the sirens of World War II. Currently in the lagoon area there are 23 active sirens (15 in the Historic Center, 3 in the islands and 5 on the coast), which usually come into operation about 3 hours in advance when a high tide is expected (> = +110 cm). So 3 hours before, you can start getting prepared. Sometimes this means helping your friends move their merchandise from their shops, putting chairs on top of tables in restaurants, moving absolutely anything you can to keep it from getting wet. The 3 hours is subject to the winds and sometimes you have only about 1.5 hours.

Grand Canal

Since 2008, a new alert system has been in place in case of high water, characterized by important innovations:

1) the locations for the sirens center of Venice has increased from the previous eight to fifteen. In this way a better coverage to the entire city is possible.

Rio Cannaregio – Usually there is a fish market here.

2)The electro-mechanical siren (ear piercing sound), has been replaced by a system of acoustic speakers which can direct the sound,

3)the new system can reproduce the sound of the current scary ear bursting sirens, but it also plays a different melody to each tide level (110 cm, 120 cm, 130 cm, 140 cm and more) OK, I do not know the tune of this melody and for the one over 140 cm, I do not want to learn.

We all have apps on our phone which alert us as well. My favorites are hiTideVenice and of course 3BMeteo.

We all keep our stivali (boots) nearby in the winter and the vendors sell “disposable” ones which have a very short life, in my opinion. They cost about 14-16 Euro, a necessary investment if you want to enjoy your visit. My favorite place to buy waterproof boots is at the fishing tackle store and you will see many Venetians in their waders, clearly from the same store. They may not be the most attractive boots you’ll ever own, but they will keep you dry.

The water creeps into the city, silently and retreats the same way about 3 hours later. If it occurs in the middle of the night, you might not even notice it. But if you experience it, you will absolutely never forget it. Don’t tell my Venetian friends, but I love it and get up in the middle of the night so I don’t miss it.

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