Climate & Hydrology

Climate & Hydrology


Guinea has a tropical monsoon climate with moist south-westerly winds during the wet season (March to October) and dry north-easterly winds during the dry season (November to February). During the wet season, local vegetation grows rapidly resulting in an accumulation of undergrowth. During the dry season with little rainfall, the shallow topsoil retains little water, leading to ideal conditions for wild fire.


Often described as a ‘water tower’, the Nimba Mountains serve as headwaters to over 40 permanent and seasonal streams. Those in Guinea flow mainly into the Cavally River, which continues into Cote d’Ivoire and then forms the border between Cote d’Ivoire and Liberia before flowing into the Gulf of Guinea. The mountains have many mid-elevation springs that flow year-round, fed by groundwater from high-elevations of the massif.


The dominant vegetation classes of the Nimba Mountains include upland several types of rainforest, including cloud forest and high-altitude savannah at the highest elevations.

Over 2,000 species of vascular plants have been identified, with more than 16 considered endemic to the region. In general, the greatest species diversity is found at lower elevations, and diversity decreases with increasing altitude. Conversely, the pattern of globally rare species increases with altitude in both forest and savannah.

Vegetation classes in the surrounding lowlands are dominated by fallow, cultivated and grazed land.

They include highly modified habitat containing many fewer species of biological value. However, these lands are interspersed with gallery forest and edaphic savannah which, while modified and degraded, still harbour biodiversity of conservation value and protect aquatic environments with species of extremely high conservation significance.


In total, 830 vertebrate species have been described in and around the Guinean Nimba Mountains. These include 76 large and medium mammals, 97 small mammals, 56 species of bat, 441 birds, 90 reptiles and 70 amphibians.

Fauna of global conservation concern in high-altitude savannah includes several critically endangered and endangered amphibians, bats and spiders including the Nimba viviparous toad (Nimbaphrynoides occidentalis, CR) and Lamotte’s roundleaf bat (Hipposideros lamottei, CR).

The Nimba Mountains lie within one of the world’s Endemic Bird Areas, and the Guinean part of the massif is recognised as one of the country’s 18 Important Bird Areas.

The Nimba Mountains Strict Nature Reserves in Guinea and Côte d’Ivoire fall within an Alliance for Zero Extinction (AZE) site. AZE sites are considered Key Biodiversity Areas (KBAs), too.

History and Conservation Status

History and Conservation Status

Archaeological remains indicate the Nimba Mountains have been inhabited for thousands of years. Their written history began a little over a century ago.

Reconciling Conservation and Human Activity

Reconciling Conservation and Human Activity

Since the late 1980s, the Guinean Government and international partners have sought how to balance the legitimate development needs and aspirations of local people and of the nation, with the imperative of protecting the unique species and ecosystems of the Nimba Mountains.