The Atlantic coasts are set to experience a spectacular yet dangerous episode of strong tides beginning Friday, March 28, 2025. With tidal coefficients exceeding 110, and peaking at 114 over the weekend, officials are urging the public to exercise extreme caution.
This weekend's great tides promise to be a sight to behold on the Breton coastline, attracting curious onlookers, photographers, and shellfish gatherers. However, the beauty of this natural phenomenon comes with significant risks. The sea can rise dramatically—up to 5 meters in just two hours—during significant tidal changes, creating hazardous conditions for those venturing near the water.
According to the Préfecture maritime de l'Atlantique, the period from March 28 to April 2 will see particularly strong tidal coefficients. Authorities are concerned about the dangers posed by stronger currents and the potential for individuals to become isolated by the rising tide. In 2024, over 50 rescues were conducted along the Atlantic coast due to similar circumstances, highlighting the need for vigilance.
On Friday, conditions will be rough, with swells reaching up to 4 meters on certain coasts. However, as the weekend progresses, the weather is expected to improve. An anticyclone is predicted to settle over the region, bringing calmer weather on Saturday and Sunday, particularly in the Côtes-d’Armor, Ille-et-Vilaine, and Morbihan areas.
Despite the anticipated pleasant weather, caution is still advised. Temperatures will hover around 11 °C, but the UV index is expected to be high (4 to 5), which can lead to unexpected sunburns, especially for those with fair skin who have not yet acclimated to the sun after winter.
Additionally, a portion of the Breton coastline is currently under a health alert due to amnesic shellfish poisoning (ASP). Areas in Morbihan, such as the Étel river, Lorient harbor, Groix, Belle-Île, Hoëdic, and Houat, are affected. This contamination has led to temporary bans on harvesting certain shellfish, including clams and periwinkles, until the health situation improves.
In southern Finistère, similar restrictions apply to the Guilvinec-Bénodet areas, Forêt Bay, and even Brest harbor. Authorities are urging anyone planning to enjoy the great tides to stay informed about the health advisories and to consult local maps and tidal schedules.
As large crowds are expected on the coastline, the SNSM (Sauveteurs en Mer) and meteorologists are calling for common sense. Visitors can enjoy the breathtaking spectacle of the great tides, but they must not underestimate the dangers posed by the sea or ignore health restrictions.
For those planning to venture out, it is essential to check tidal schedules, monitor weather conditions, and ensure proper equipment is carried, including a reliable means of communication, a charged phone, and suitable clothing. It is also crucial to avoid going alone and to inform someone of your plans.
The following are the tidal schedules for the great tides in Brittany from March 29 to March 31, 2025:
Côtes-d’Armor
Erquy
Saturday, March 29: BM 1:18 AM – PM 6:58 AM (11.79 m) / BM 1:42 PM – PM 7:21 PM (12.82 m)
Sunday, March 30: BM 3:03 AM – PM 8:41 AM (12.25 m) / BM 3:26 PM – PM 9:02 PM (12.12 m)
Monday, March 31: BM 3:44 AM – PM 9:21 AM (12.35 m) / BM 4:06 PM – PM 9:40 PM (12.10 m)
Baie de Saint-Brieuc – Le Légué
Saturday, March 29: BM 1:17 AM – PM 7:01 AM (11.76 m) / BM 1:43 PM – PM 7:25 PM (11.75 m)
Sunday, March 30: BM 3:03 AM – PM 8:45 AM (12.24 m) / BM 3:27 PM – PM 9:06 PM (12.08 m)
Monday, March 31: BM 3:45 AM – PM 9:26 AM (12.38 m) / BM 4:07 PM – PM 9:45 PM (12.10 m)
Finistère
Roscoff
Saturday, March 29: BM 12:00 AM – PM 5:55 AM (9.25 m) / BM 12:22 PM – PM 6:20 PM (9.19 m)
Sunday, March 30: BM 1:43 AM – PM 7:38 AM (9.54 m) / BM 2:04 PM – PM 8:00 PM (9.39 m)
Monday, March 31: BM 2:24 AM – PM 8:19 AM (9.59 m) / BM 2:45 PM – PM 8:39 PM (9.11 m)
Morbihan
Lorient – Port-Louis
Saturday, March 29: PM 4:25 AM (5.42 m) / BM 10:35 AM – PM 4:44 PM (5.30 m) / BM 10:54 PM
Sunday, March 30: PM 6:06 AM (5.57 m) / BM 12:16 PM – PM 6:23 PM (5.40 m)
Monday, March 31: PM 0:36 AM (5.55 m) / BM 12:58 PM – PM 7:02 PM (5.36 m)
The next episodes of great tides with coefficients exceeding 100 are scheduled for April 26 to April 30, 2025, with a maximum coefficient of 108, and again from September 8 to September 11, 2025, with a maximum coefficient of 106.
As the tides rise, the message from authorities is clear: enjoy the beauty of nature, but respect its power and stay safe.
