Embrace the Rains: Understanding Monsoon Season in Africa

Introduction

Africa, spanning two hemispheres, is a continent of extremes. Many people think Africa is hot year around, however, the Americas, Africa, Australia and Asia all have monsoon climates at tropical and subtropical latitudes. Monsoon seasons can actually fail, bringing intense drought and famines to many parts of the world. A monsoon is a large scale weather pattern which causes our summer thunderstorms.

Understanding the Monsoon

The term monsoon generally refers to the seasonal reversal in atmospheric low-level circulations, particularly the surface winds and associated precipitation, resulting in a pattern of wet summers and dry winters. Monsoon circulations are present over many regions of the world, including Africa. Usually, the term monsoon is used to refer to the rainy phase of a seasonally changing pattern, although technically there is also a dry phase. The term is also sometimes used to describe locally heavy but short-term rains. The major monsoon systems of the world consist of the West African, East African, and Southern African monsoons.

Regional Variations in Monsoon Seasons

Monsoon patterns vary significantly across Africa, influenced by the continent's diverse geography and proximity to different ocean currents. Let's dive into the distinct characteristics of the West African, East African, and Southern African monsoon systems.

West African Monsoon

The West African Monsoon (WAM), which brings the majority of the annual rainfall to the region, is a complex system influenced by various internal and external factors, including sea surface temperature (SST) variability, green-house gas concentrations, and land-surface changes (Charney et al., 1975; Claussen and

East African Monsoon

The East African Monsoon is associated with the ITCZ moving south of the equator. The so-called long rains prevail during spring (MAM) and the short rains during autumn (OND). Thus the transition (equinox) seasons bring most rainfall to East Africa (Figure right panel). It occurs from December to February north of the equator, and from June to September south of the equator. During the long rainy season, rain comes in heavy but short afternoon downpours. Non-equatorial countries in Central Africa have more distinct weather patterns.

Southern African Monsoon

In southern Africa, the rainy season typically lasts from October to April and reaches maximum strength between November and March. Most locations receive more than 75% of their annual precipitation during this 7-month period, with some parts in the northwest receiving more than 90% of their total annual rainfall. Deadly flooding has replaced the dry start to the 2014-2015 southern Africa monsoon, and the wet season has several months left go.

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