The Climate of West Africa: A Region of Contrasts and Change

Dec 13, 2025 0

West Africa, also known as Western Africa, is the westernmost region of Africa. The region covers one fifth of Africa, with an area of 6 million km². This vast area is home to diverse landscapes and complex climate patterns that significantly influence the environment and the lives of its inhabitants.

Climate zones of Africa, showing the ecological break between the Sahara Desert (red), the hot semi-arid climate of the Sahel (orange) and the tropical climate of Central and Western Africa (blue).

Geographical and Historical Context

Historically, West Africa was home to several powerful states and empires that controlled regional trade routes, including the Mali and Gao Empires. Positioned at a crossroads of trade between North Africa and sub-Saharan Africa, the region supplied goods such as gold, ivory, and advanced iron-working. During European exploration, local economies were incorporated into the Atlantic slave trade, which expanded existing systems of slavery. Even after the end of the slave trade in the early 19th century, colonial powers - especially France and Britain - continued to exploit the region through colonial relationships, continuing to export extractive goods like cocoa, coffee, tropical timber, and mineral resources.

West Africa has a rich ecology, with significant biodiversity across various regions. Its climate is shaped by the dry Sahara to the north and east - producing the Harmattan winds - and by the Atlantic Ocean to the south and west, which brings seasonal monsoons. This climatic mix creates a range of biomes, from tropical forests to drylands, supporting species such as pangolins, rhinoceroses, and elephants.

Climatic Zones and Growing Seasons

The West African region can be divided into four climatic sub-regions namely the Guinea Coast, Soudano-Sahel, Sahel (extending eastward to the Ethiopian border) and the Sahara, each with different climatic conditions.

Read also: Mauritius Climate Guide

The region's climate is greatly affected by rainfall, which largely determines the distribution of vegetation. The vegetation zones include:

Rainforest: Found in areas of high rainfall, such as Sierra Leone and southern Nigeria.
Savannah: Characterized by isolated trees and oil palms, with increasing distances inland.
Tropical Xerophytic Woodland: Located on the edge of the desert, with species like Baobab and Shea Butter.

These climatic zones influence agricultural practices and the distribution of tsetse flies, impacting livestock rearing.

WEST AFRICA; CLIMATIC ZONES AND GROWING SEASON.

The West African Monsoon

The West African monsoon is a major wind system that affects West African regions between latitudes 9° and 20° N. It is characterized by winds that blow southwesterly during warmer months and northeasterly during cooler months of the year.

The main characteristics of the West African seasons have been known to the scientific community for more than two centuries. The West African monsoon is the alternation of the southwesterly wind and the harmattan at the surface. Such alternation is normally found between latitudes 9° and 20° N. Northeasterlies occur constantly farther north, but only southwesterlies occur farther south.

The southwest winter monsoon flows as a shallow humid layer of surface air (less than 2,000 metres [about 6,600 feet]) overlain by the primary northeast trade wind, which blows from the Sahara and the Sahel as a deep stream of dry, often dusty air. As a surface northeasterly, it is generally known as the harmattan, gusty and dry in the extreme, cool at night and scorchingly hot by day.

The advancing fringe of the southwest monsoon is too shallow (under 1,000 metres [3,300 feet]) for many thunderstorms and other disturbances to occur. They usually occur 200-300 km (about 125-185 miles) behind the fringe, where the moist air is deeper (1,000-2,000 metres [3,300-6,600 feet]) but the ground is still hot enough to make it very unstable.

The southwest monsoon dominates the weather, and clouds and rain abound. The rain is primarily due to coalescence of droplets, with most of the clouds located below 3,500 metres (11,500 feet).

Rainfall Patterns

Rainfall in West Africa varies significantly in amount and duration, influenced by ocean currents and physiographic features. Some key points include:

Annual rainfall ranges from 175mm to over 10,000mm.
Dakar has only 585mm annual rainfall due to its location on coastal Senegal.
The mountainous region of Cameroon has over 10,000mm of annual rainfall.

Rainfall is influenced by migrating air masses and the Intertropical Convergence Zone (ITCZ). Temperatures are generally above 18°C, with mean annual temperature ranges from 10° - 35°C.

Read also: Impact of Climate on Africa

Climate Change and its Impacts

Climate change in Africa is a serious threat as Africa is one of the most vulnerable regions to the effects of climate change, despite contributing the least to causing it. Climate change is causing increasingly erratic rainfall patterns, more frequent extreme weather events including droughts, floods, and rising sea surface temperatures in Africa. Climate change intensifies existing socioeconomic vulnerabilities.

On average African countries face climate-related losses amounting to 2-5% of GDP annually, while adaptation costs in sub-Sahran Africa are projected at USD 30-50 billion per year over the next decade. Africa's climate change adaptation strategies focus on building resilience through climate-smart agriculture, sustainable water management, ecosystem conservation, and strengthening health and infrastructure systems.

During the dry period, the Sahel experienced a number of particularly severe drought events, with devastating effects. The recent decades, have also witnessed a moderate increment in annual rainfall since the beginning of 1990s. Since 1985, 54 percent of the population has been affected by five or more floods in the 17 Sahel region countries. In 2012, severe drought conditions in the Sahel were reported. Fifteen percent of Sahel region population has also experienced a temperature increase of more than 1 °C from 1970 to 2010.

Climate change, due primarily to burning oil, coal, and methane gas, is causing hotter temperatures to become more frequent in the four West African countries responsible for producing approximately 70% of the world’s cacao - the key ingredient in chocolate. Analysis of daily maximum temperatures during the past decade shows that climate change added at least three weeks above 32°C (89.6°F) annually during the main cacao crop season (October-March) in Côte d'Ivoire and Ghana. Such temperatures are above the optimal temperature range for cacao trees.

In February 2024, western Africa was hit by unusually intense heat. Climate change made the heatwave 10 times more likely and 4C hotter. Extreme heat is particularly dangerous when combined with high humidity. To assess the severity of the hot and humid conditions, the study authors analysed the “heat index”.

Five-day average heat index over 11-15 February (left), and the difference compared to the 1991-2020 average (right), using ERA5 reanalysis data.

The graphic below illustrates these results. The square on the left shows a world without climate change, in which such a heatwave would happen less than once every 100 years. The middle square shows that in today’s climate, the heatwave is a one-in-10 year event.

Expected frequency of the February 2024 west African drought at different warming levels.

Deforestation and Overfishing

West Africa is greatly affected by deforestation and has one of the worst deforestation rate. Huge swaths of forest are being razed to clear space for palm oil and cocoa plantations. Mangroves are being killed off by pollution. Even wispy acacias are hacked away for use in cooking fires to feed growing families. Nigeria, Liberia, Guinea, Ghana and the Ivory Coast, have lost large areas of their rainforest. In 2005, the Food and Agriculture Organization of the United Nations ranked Nigeria as the state with the worst deforestation rate in the entire world.

Overfishing is a major issue in West Africa. Besides reducing fish stocks in the region, it also threatens food security and the livelihoods of many coastal communities that largely depend on artisanal fishing. To combat the overfishing, Greenpeace has recommended countries reduce the number of registered trawlers operating in African waters, increase the monitoring and control and set up regional fisheries organizations. Some steps have already been taken in the form of WARFP (the World Bank's West Africa Regional Fisheries Program which empowers west-African countries (i.e. Liberia, Sierra Leone, Cape Verde, and Senegal) with information, training and monitoring systems.

Here's a summary of the key facts related to climate change in West Africa:

Key Fact	Description
Increased Temperatures	Climate change is causing temperatures to become more frequent in West Africa.
Cocoa Production	West African countries produce approximately 70% of the world's cacao.
Heatwave	In February 2024, western Africa was hit by an unusually intense heatwave. Climate change made the heatwave 10 times more likely and 4C hotter.
Deforestation	West Africa is greatly affected by deforestation and has one of the worst deforestation rates.
Overfishing	Overfishing is a major issue in West Africa, threatening food security and livelihoods.

The people of West Africa and their leaders must navigate an increasingly complex path, to meet the immediate needs of a growing population while protecting the environment that will sustain it into the future.