Camille Moreau / Photo credits: PHILIPPE TURPIN / PHOTONONSTOP / PHOTONONSTOP VIA AFP 7:24 a.m., March 10, 2024

At this time of year, when day and night have exactly the same length, the north and west of France prepare for spectacular high tides, called "equinox tides".

A phenomenon that occurs twice a year, but which promises to be even more intense than usual this year.

Mont-Saint-Michel or even Saint-Malo with its feet in the water?

From Sunday to Tuesday, the west and north coast will face exceptional high tides, called equinox tides, this time of year when day and night have exactly the same duration.  

A phenomenon which therefore takes place twice a year, but which will be "a little more important than usual", indicates, to Europe 1, Pierre Garreau, oceanographer at IFREMER.

According to the researcher, “this is due to the configuration of the stars which is particularly favorable”. 

A risk of flooding by the sea

“When the moon and the sun work together, we have a big tide, a kind of very big wave. The waters will rise higher and fall lower,” he continues.

Normally, the coefficient of a classic high tide is around 90, while exceptional high tides, such as the expected one, “around 115”. 

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This equinox tide may not be completely without consequences.

“What we can fear is that there will be floods along the seaside with water rising on the quays,” explains Pierre Garreau.

If a storm were to occur, "the atmospheric pressure is lower and the water rises by around 40cm more than predicted by the tide calculation. So that can make the difference", concludes the specialist.