🇲🇷Mauritania

Mauritania spans 14°43′–27°18′N as a vast (~1,030,700 km²) northwest African country bordering Algeria, Mali, Senegal, and Western Sahara, with a 754 km Atlantic coast. Approximately 75 percent of the country is Saharan desert: the Adrar plateau, Kediet ej Jill near Zouérat (915 m, the country's highest peak), the Tagant plateau, the great ergs (Erg Igidi, Erg Chech) of dunes, and the iconic Richat Structure (the Eye of the Sahara) in the Adrar.

Thinner Sahel and Sudanian savanna fringes lie in the deep south along the Senegal River. This produces a sharp climate gradient: hot desert (BWh) across the vast central and northern interior, hot semi-arid (BSh) in the southern Sahel, and a unique cool-coast desert on the Atlantic at Nouadhibou where the cold Canary Current produces remarkably temperate temperatures.

Nouakchott on the cool Atlantic coast sees highs of 29°C and lows of 15°C in January and highs of 35°C and lows near 25°C in September with 90 mm rainfall, almost entirely in the brief August–September monsoon. Nouadhibou on the Atlantic registers highs of about 24°C and lows of 14°C in January and highs of 30–31°C and lows of 20°C in September with 30 mm: extraordinary cool-coast aridity. Atar in the Adrar sees highs of 28°C and lows near 13°C in January and highs of 42°C and lows of 27°C in July with roughly 30 to 110 mm. Rosso on the Senegal River records daily means of about 23°C in January and 30°C in May.

Néma in the southern Sahel receives about 280 mm a year. In the Saharan zone, May to July temperatures range from about 16°C in the early morning to more than 49°C by the afternoon. Major events include the severe Sahel drought of 1968–73, which drove many Mauritanians to Nouakchott, the renewed drought of 1983–84, frequent harmattan sandstorms, and a desert that has been expanding since the mid-1960s.

Comparing the last decade against the 1940–1970 baseline, mean temperatures across these cities have risen by about 0.8°C.