🇬🇳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 1,538 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 rainforest (Af) in the southeast.

Conakry on the Atlantic coast averages 27°C year-round with 3,800 mm of rainfall, ranking among Africa's wettest cities, 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 with annual means of 21–23°C, 1,800–2,500 mm of rainfall, and frequent morning fog.

Kankan in Upper Guinea records 27°C with 1,580 mm falling in a single wet season. The southeastern forest belt around Macenta and Nzérékoré receives 2,000–2,500 mm in a strong May–October wet season. Major climate hazards include intensifying Sahel-margin droughts in Upper Guinea, recurrent severe wet-season flooding in Conakry during 2014, 2015, and 2019, accelerating deforestation and bauxite-mining-driven environmental stress on the Fouta Djallon water towers that feed the Niger and Senegal, and intensifying coastal erosion at Kamsar and Boké.

Our archive covers 12 Guinean cities with daily ERA5 reanalysis data going back to 1940. The warmest July averages occur in Siguiri, around 29.2°C, while Labé records the coldest January nights 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.