🇬🇳Guinea

Guinea spans 7°10′–12°40′N, a West African country of approximately 245,857 km² on the Atlantic coast bordering Guinea-Bissau, Senegal, Mali, Côte d'Ivoire, Liberia, and Sierra Leone. The nation comprises four distinct natural regions: coastal Lower Guinea including Conakry and Boké, the Fouta Djallon plateau in the centre rising to Mount Loura at over 1,500 m and serving as the source of the Niger, Senegal, and Gambia rivers, the Upper Guinea savanna around Kankan, and the Forested Guinea highlands in the southeast crowned by Mount Nimba at 1,752 m. This topography produces a strong climate gradient from tropical monsoon (Am) on the coast, through tropical savanna (Aw) in Upper Guinea, to tropical monsoon (Am) and savanna (Aw) in the forested southeast.

Conakry on the Atlantic coast has highs of 28–32°C and nights of 22–25°C year-round with 3,800 mm of rainfall, with precipitation almost entirely concentrated from May to November and a long bone-dry Harmattan-influenced winter. The Fouta Djallon plateau at Labé and Mamou is significantly cooler at night, with lows of about 12–20°C and 1,500–1,800 mm of rainfall.

Kankan in Upper Guinea sees highs of 30–38°C and nights of 15–24°C with 1,440 mm falling in a single wet season. The southeastern forest belt around Macenta and Nzérékoré receives 1,900–2,700 mm in a long March–November wet season. Major climate hazards include intensifying Sahel-margin droughts in Upper Guinea, recurrent severe wet-season flooding in Conakry, accelerating deforestation and bauxite-mining-driven environmental stress on the Fouta Djallon water towers that feed the Niger and Senegal, and intensifying coastal erosion.

Our archive covers 12 Guinean cities with daily ERA5 reanalysis data going back to 1940. The hottest July afternoons are in Siguiri, with average highs around 29.2°C, while Labé has the coldest January nights, with average lows near 15.9°C. Comparing the last decade against the 1940–1970 baseline, mean temperatures across these cities have risen by about 1.2°C.