Mauritania experiences a desert climate on the western edge of the Sahara, air temperatures reach a minimum of 4°C in September, averaging between 20°C and 22°C, apart from in July and October when temperatures average 24°C. During the cold season, water temperature may increase by as much as 10.8oC from 100 m depth to the surface. Four types of water masses interact off Mauritania:
Upwelling is one of most important characteristics of Mauritanian waters; indeed this phenomenon is the reason for the abundant marine resources found here, particularly in the Arguin Bank Park, where phytoplankton blooms support a productive food web. Upwelling occurs all year round in the north and only 9 months of the year in the southern costs. The broad Mauritanian Current flows northwards and meets the wind-driven Saharan Current flowing southwards over the continental shelf, creating anticyclonic flow.