The climate of Africa is highly variable, ranging from equatorial to desert conditions. While temperatures are consistently high, rainfall patterns differ significantly across the continent. The African wet season is a crucial period, influencing agriculture, water resources, and overall socio-economic stability. This article delves into the key characteristics of the African wet season, exploring monsoon patterns, rainfall distribution, and the impact of climate change.
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).
West African Monsoon
The West African monsoon is a major wind system affecting 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 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 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.
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Rainfall Patterns
Except for erratic rains in the high-sun season (June-August), the whole year is more or less dry at 20° N. The drought becomes shorter and less complete farther south. At 12° N it lasts about half the year, and at 8° N it disappears completely. Farther south a different, lighter drought begins to appear in the high-sun months when the monsoonal southwesterly is strongest.
This drought results from the arrival of dry surface air issuing from anticyclones formed beyond the Equator in the Southern Hemisphere and is thus similar to the monsoonal drought in Java. The moist southwesterly stream, particularly frequent between 5° and 10° N, can reach much farther north, bringing warm humid nights and moderately hot but still humid days.
The harmattan brings cooler nights, but the extreme daily heating causes a thermal range of 10-12 °C (18-22 °F). Even in the daytime, the harmattan may give a sensation of coolness to the human skin as it evaporates moisture from the skin’s surface.
Monsoon Dynamics
The alternation of the two winds is seasonal on the basis of overall frequency, but in fact it varies considerably with the synoptic pressure patterns. 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 tops of cumulonimbus clouds may reach 12,000 metres (about 39,000 feet), well above freezing level (4,200-4,500 metres [13,800-14,800 feet]).
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The disturbances usually occur along a given longitude line that is slightly curved and may in fact form one long line squall. They also reach 12,000 metres or more, traveling steadily westward at 37 to 56 km (23 to 35 miles) per hour. This suggests that they originate in the primary trade wind aloft and, as in India, are probably related to the tropical easterly jet stream.
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). If it were not for the change in wind direction when the southeast trades have crossed the Equator, the monsoon system of West Africa could not be distinguished from the weather system, caused by the seasonal shift in the latitude of the intertropical convergence, as experienced over most of Central Africa.
On the south coast, which is at latitude 4° N to 6° N, the southwest monsoon (as the intertropical convergence) may occur at any time, but the results are quite atypical for various reasons. In the low-sun season (December-February), the southwesterly is rare and ineffective, and the weather is cloudy but dry.
From April to June, the midday sun is at its highest, and insolation (solar radiation received at Earth’s surface) is most intense. Because the southwest wind occurs most frequently, the consequent building up of clouds leads to the main rainy season.
During July and August (the short drought), cloudy conditions prevail, but the air issues direct from anticyclones farther south and is dry, in spite of the fact that its direction of flow does not change. Toward the north, conditions are more distinctly monsoonal: by latitude 8° N the two wet seasons have merged into one long “wet” with two subdued peaks, which last approximately seven to eight months (March-October). The “dry,” which is controlled by northeast winds, lasts from November to early March.
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Climate Change in Africa | Global 3000
Regional Climate Variations
The climate across Africa varies significantly. Great parts of North Africa and Southern Africa as well as the whole Horn of Africa mainly have a hot desert climate, or a hot semi-arid climate for the wetter locations. The Sahara Desert in North Africa is the largest hot desert in the world and is one of the hottest, driest and sunniest places on Earth. Located just south of the Sahara is a narrow semi-desert steppe (a semi-arid region) called the Sahel, while Africa's most southern areas contain both savanna plains, and its central portion, including the Congo Basin, contains very dense jungle (rainforest) regions. The western equatorial region is the wettest portion of the continent.
Kenya's Climate
It’s generally sunny, dry and temperate most of the year in Kenya despite being situated directly on the equator. Central Kenya’s Laikipia Plateau is situated at an altitude that keeps temperatures comfortable. Coastal areas are obviously hotter, but the ocean breeze helps to maintain pleasant conditions for most of the year.
There are two rainy seasons-the heaviest rains (called masika) usually fall from mid-March to May and a shorter period of rain (called vuli) occurs in November and December. January and February are mostly dry, although there may be a chance of rain. The dry season, with cooler temperatures, lasts from May to October.
Many travelers assume that because they are traveling to Africa, it must always be warm. This is not the case in Kenya during the night and early morning, however, particularly in June, July and August. You can expect days to be absolutely beautiful, temperate and sunny, but nights and early mornings will be chilly, possibly near freezing, so we recommend you bring warm layers you can peel off as it warms up through the day. A lightweight down jacket or fleece pullover is ideal. Gloves, hat, scarf and warm long pants are also essential at this time of year for early-morning wildlife drives.
Here's an overview of Kenya's monthly weather:
| Month | Description | Recommendations |
|---|---|---|
| January | Hot and dry. Temperatures gradually increase. Average highs range from the mid-70s F to the mid-80s F, while average lows range from the mid-50s F to the mid-60s F. | Short-sleeved shirt, shorts or zip-off pants, sunscreen, and a wide-brimmed hat. A lightweight, long-sleeved shirt may also be useful for shielding your arms from the sun. |
| February | Hot and dry with long, hot, sunny days and little or no rain. Usually the hottest month of the year. Highs are typically in the upper 70s F to low 90s F. | Short-sleeved shirt, shorts or zip-off pants, sunscreen, and a wide-brimmed hat. A lightweight, long-sleeved shirt may also be useful for shielding your arms from the sun. |
| March | Still hot, although it sometimes brings the beginning of the long rains, which last until June. As summer comes to an end, highs will be mainly in the 80s F. Average lows will be in the mid-50s F to mid-60s F. | Rain gear, including a rain jacket or lightweight poncho and rain pants. |
| April | The true beginning of the long rainy season, which is likely to bring either lengthy periods of rain or sporadic heavy downpours in the late afternoon. All this moisture turns the landscape lush and green. When it is not raining, daytime temperatures will be warm, with highs in the upper 70s and 80s F. At night it may cool down into the upper 50s F. | A lightweight, “breathable,” waterproof rain jacket, rain pants and inexpensive rain poncho. |
| May | Much the same as April, May is characterized by heavy rains. It also marks the beginning of winter. High temperatures are generally in the mid- to upper 70s F and lows are usually in the 50s F. | Raingear is a must, with a lightweight, “breathable,” waterproof rain jacket, rain pants and inexpensive rain poncho for the best protection. |
| June | By June the rains have typically subsided, and the drier winter season has arrived in Kenya (although you may still want a rain jacket just in case). High temperatures are usually in the 70s F while lows are mostly in the 50s F. | A sweater or fleece at night and in the early mornings, as well as a warm hat, gloves and a scarf for early morning wildlife drives that may take place in open vehicles. |
| July | Winter continues through July with high temperatures in the 70s F and lows in the 50s F. Nights and early mornings can be very chilly, especially during wildlife drives in open vehicles. | A warm fleece jacket as well as a hat, gloves and scarf. As the day warms up you’ll want to shed these layers and will likely be most comfortable in a T-shirt and shorts or zip-off pants. |
| August | August is the final month of winter in Kenya, and conditions are very similar to those in July. High temperatures will be in the 70s F with lows in the 50s F. Nights and early mornings can be very chilly, especially during wildlife drives in open vehicles. | A warm fleece jacket as well as a hat, gloves and scarf. As the day warms up you’ll want to shed these layers and will likely be most comfortable in a T-shirt and shorts or zip-off pants. In the Maasai Mara, light rain showers are possible in the afternoons and evenings. |
| September | September in Kenya is characterized by the end of winter. It is typically dry with high temperatures in the upper 70s and low 80s F and lows in the mid-50s to low 60s F. | A warm fleece jacket as well as a hat, gloves and scarf. As the day warms up you’ll want to shed these layers and will likely be most comfortable in a T-shirt and shorts or zip-off pants. In the Maasai Mara, light rain showers are possible in the afternoons and evenings. |
| October | Kenya’s short rains begin in October. High temperatures generally range from the upper 70s to the low 90s F, with lows in the upper 50s to mid-60s F. | Be prepared for rain showers with a lightweight, “breathable,” waterproof rain jacket, rain pants and inexpensive rain poncho. You will also likely want a T-shirt and shorts or zip-off pants for warmer periods when the sky clears and the sun is out. |
| November | The short rains continue into November, and travelers should be prepared for conditions similar to those in October. | |
| December | By December the short rains have ended for the most part, and, as summer begins, Kenya tends to be sunny and dry. High temperatures tend to be in the 70s and 80s F, while lows are in the mid-50s and 60s F. | For the hot daytime temperatures, we recommend a short-sleeved shirt, shorts or zip-off pants and plenty of sun protection, including sunscreen and a wide-brimmed hat. A lightweight, long-sleeved shirt may also be useful in shielding your arms from the sun. |
South Africa's Climate
South Africa has two distinct weather patterns. Cape Town, Garden Route and winelands enjoy a dry summer between October and March making it the ideal time of the year to travel to the Cape.
South Africa’s marginal zones are influenced by the effects of the respective oceans’ currents. The Indian Ocean is warmed by the south flowing Agulhas, its moist air mass providing the coastline of Kwazulu-Natal and much of that of the Eastern Cape with their high levels of humidity, their tropical feel. The Atlantic, on the other hand, is cooled by the north flowing Benguala current, and its dry air mass produces arid conditions along much of South Africa’s western coasts.
Generally speaking, therefore, the wet season, the southern hemisphere’s summer, occurs between October and March, the dry season, its winter, June through to August, while spring is September and Autumn April and May. Depending on where you are in the country, daytime temperatures for the wet season can push up into the early thirties, making travelling a somewhat hot and humid affair.
Given the above, it is possible to travel to South Africa at any time of the year, with Cape Town, the fynbos and the winelands offering an ‘out of season’ experience. However, the majority of wildlife areas are not situated in the Western Cape.
During the wet season, the animals are afforded greater cover, are more widely dispersed and therefore are much more difficult to spot. This said, it is also true to say that some experienced travellers and specialists prefer the wet season: the game is in better shape; it is when many species calve; behaviour changes; and it is the time for watching birds.
The Sahel Region
The name Sahel refers to the semi‐arid region stretching longitudinally from Senegal in West Africa to Sudan and Ethiopia in East Africa and latitudinally from just north of the tropical forests to just south of the Sahara desert (roughly between 10° and 20°N). Across this vast expanse, seasonal rainfall varies sharply in the meridional direction but much less in the zonal direction.
The climatology is well described by the meridional movement of a zonal rain band whose summertime northward progression produces a single rainy season: ramping up around May, winding down by October, and with the bulk of the annual rainfall falling between June and September.
Annual mean rainfall decreases from more than 800 mm in the south to less than 200 mm in the north and determines the progression of natural land cover from shrublands to grasslands and savanna, and the prevalence of sedentary agriculture or nomadic pastoralism.
Across the region, abundance or scarcity of rainfall-as well as its distribution over the rainy season and the associated maximum temperature extremes-determines the success or failure of smallholder farming systems, which are often rain‐fed.
Climate Change 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. Large segments of the African population depend on climate-sensitive livelihoods such as agriculture (55 - 62% of the workforce in sub-Saharan Africa) and already live in poverty, heightening their exposure to shocks.
Agriculture is one of the most vulnerable sectors, as most African farmers rely on rainfed crops. Reduced and unpredictable rainfall, combined with higher temperatures, drives soil moisture loss, desertification (especially in the Sahara) and shifts suitable growing areas. These changes lower yields of staple crops, undermining food security and worsening hunger.
The economic toll of climate change is severe. 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.
In chapter 9 of the IPCC Sixth Assessment Report, it is reported that although greenhouse gas emissions are among the lowest in Africa, anthropogenic climate change has severely threatened daily life. People experience extreme food insecurity, high mortality rates, major biodiversity loss, and more as a result of global warming.
