It is more correct to say - in the ocean. The warmest water at the resort in August is about +21-22°C, in July and September it is a few degrees lower. From the second half of September the water gradually cools down, and in early October its temperature is +18°C.
In winter, the temperature in the Atlantic Ocean drops to +8°C. In early to mid June, the water temperature in the Atlantic Ocean is already high enough to open a full-fledged beach season. So at the end of May you can happily tell your friends: "I'm going to La Baule!".
