Saint-Louis is part of the Sahelien zone. This desertic band separates the dunes of the Sahara from the baobabs of the savanna. This transitional area is characterized by the emergence of a few fixed dunes by prickly accacias. These are practically the last trees that still survive naturally in this dry region. The sandy ground is frequently stirred up by winds, creating sand storms that can last several days. These happen more frequently during the period of Harmattan (December to Mai), this famous dry and hot wind that comes down from the Saharan desert. During the rainy season, the ground is covered by a layer of grass. The bushes also regain their greenery, transforming the landscape nicely.
During the rainy season, when the river overflows into the countryside, Saint Louis is surrounded by flood basins. The salt water creates small ponds and stretches of mangroves. Many birds come here to feed, including flamingos and pelicans. When the river regains its course, and the ponds slowly evaporate, salt is concentrated in them, giving them a pinkish hue. Once the water is completely evaporated, the surrounding villages, such as Gandiol, harvest this salt to sell it in the market.
The Langue de Barbarie
This stretch of sand is the culmination of a beach that is close to 600 km long, from Nouâdhibou in Mauritania, to Saint-Louis. The Langue de Barbarie separates, during 25 kms, the river Senegal from the Atlantic ocean. At their junction, the waters meet with force. Its width is only a dune bordered with beaches. On one side, the pounding of the ocean : several dangerous sand bars that the fishermen need to cross daily. On the other side, the calm of the river, home to many marine birds. The vegetation consists mainly of Filao trees, which are resistant to the salty air.
Climate : The seasons
- There are only two seasons in Saint Louis, which are defined by precipitation rather than by temperature variations.
- The rainy season : it starts at the end of June and ends by mid October. It is characterized by the heat and the humidity. It is also the time storms role through, at the rate of about one a week.
- The dry season : from November to May, the climate is very agreeable during this priod as Saint Louis is cooled by the ocean breeze. Nevertheless, from January to March, the Harmattan winds come down from the desert bringing along dust that can last a few days.