Geography and climate
South Africa occupies the southernmost part of the African continent, stretching latitudinally from 22° to 35° S and longitudinally from 17° to 33° E.
Its surface area is 1 219 090 km2. The country has common boundaries with Namibia, Botswana and Zimbabwe, while Mozambique and Swaziland lie to the north-east. Completely enclosed by South African territory in the south-east is the mountain kingdom of Lesotho.
To the west, south and east, South Africa borders on the Atlantic and Indian oceans. Isolated, some 1 920 km south-east of Cape Town in the Atlantic, lie the Prince Edward and Marion islands, annexed by South Africa in 1947.
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The ocean surrounds South Africa on three sides – to the west, south and east and has a coastline of about 3 000 km. Two major ocean currents sweeps the coastline – the warm south-flowing Mozambique-Agulhas and the cold Benguela.
The Mozambique-Agulhas skirts the east and south coasts as far as Cape Agulhas, while the Benguela current flows northwards along the west coast as far as southern Angola.
The contrast in temperature between these two currents partly accounts for important differences in climate and vegetation between the east and west coasts of South Africa.
It also accounts for the differences in marine life. The cold waters of the west coast are much richer in oxygen, nitrates, phosphates and plankton than those of the east coast. Consequently, the South African fishing industry is centred on the west coast.
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The coastline itself is an even, closed one with few bays or indentations naturally suitable for harbours. The only ideal natural harbour along the coastline is Saldanha Bay on the west coast. However, the area lacks fresh water and offers no natural lines of penetration to the interior.
Most river mouths are unsuitable as harbours because large sandbars block entry for most of the year. These bars are formed by the action of waves and currents, and by the intermittent flow, heavy sediment load and steep gradients of most South African rivers. Only the largest rivers, such as the Orange and Limpopo, maintain narrow permanent channels through the bars. For these reasons, the country has no navigable rivers.
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South Africa’s surface area falls into two major physiographic categories: the interior plateau, and the land between the plateau and the coast. Forming the boundary between these two areas is the Great Escarpment, the most prominent and continuous relief feature of the country. Its height above sea level varies from about 1 500 m in the dolerite-capped Roggeveld scarp in the south-west, to a height of 3 482 m in the KwaZulu-Natal Drakensberg.
Inland from the escarpment lies the interior plateau, which is the southern continuation of the great African plateau stretching north to the Sahara Desert.
The plateau itself is characterised by wide plains with an average height of 1 200 m above sea level. The dissected Lesotho plateau, which is more than 3 000 m above sea level, is the most prominent. In general, the escarpment forms the highest parts of the plateau.
Between the Great Escarpment and the coast lies an area which varies in width from 80 km to 240 km in the east and south, and a mere 60 km to 80 km in the west. At least three major subdivisions are recognised: the eastern plateau slopes, the Cape folded belt and adjacent regions and the western plateau slopes.
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The subtropical location, on either side of 30° S, accounts for the warm temperate conditions so typical of South Africa, making it a popular destination for foreign tourists.
The country also falls squarely within the subtropical belt of high pressure, making it dry, with an abundance of sunshine.
The wide expanses of ocean on three sides of South Africa have a moderating influence on its climate. More apparent, however, are the effects of the warm Agulhas and the cold Benguela currents along the east and west coasts respectively. While Durban (east coast) and Port Nolloth (west coast) lie more or less on the same latitude, there is a difference of at least 6° C in their mean annual temperatures.
Gale-force winds are frequent on the coasts, especially in the south-western and southern coastal areas.
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South Africa has an average annual rainfall of 450 mm, compared with a world average of 860 mm. About 65% of the country receives less than 500 mm per year, which is generally accepted as the minimum amount required for successful dry-land farming.
About 21% of the country, mainly the arid west, receives less than 200 mm per year.
In Cape Town, the capital city of the Western Cape, the average rainfall is highest in the winter months, while in the capital cities of the other eight provinces, the average rainfall is highest during summer.
South Africa’s rainfall is unreliable and unpredictable. Large fluctuations in the average annual rainfall are the rule rather than the exception in most areas of the country.
Below-average annual rainfall is more commonly recorded than above-average total annual rainfall. Drastic and prolonged droughts periodically afflicts South Africa. These droughts often end in severe floods.
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Temperature conditions in South Africa are characterised by three main features. Firstly, temperatures tend to be lower than in other regions at similar latitudes, for example, Australia. This is due primarily to the greater elevation of the subcontinent above sea level.
Secondly, despite a latitudinal span of 13 degrees, average annual temperatures are remarkably uniform throughout the country. Owing to the increase in the height of the plateau towards the north-east, there is hardly any increase in temperature from south to north as might be expected.
The third feature is the striking contrast between temperatures on the east and west coasts. Temperatures above 32° C are fairly common in summer, and frequently exceed 38° C in the lower Orange River Valley and the Mpumalanga Lowveld.
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Frost, humidity and fog
Frost often occurs on the interior plateau during cold, clear, winter nights, with ice forming on still pools and in water pipes. The frost season (April to October) is longest over the eastern and southern plateau areas bordering on the escarpment. Frost decreases to the north, while the coast is virtually frost-free.
Average annual relative humidity readings show that, in general, the air is driest over the western interior and the plateau. Along the coast, the humidity is much higher, and at times may rise to 85%. Low stratus clouds and fog frequently occur over the cool west coast, particularly during summer. The “mist belt” along the eastern foothills of the escarpment is the only other area that commonly experiences fog.
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South Africa is famous for its sunshine. Generally speaking, April and May are the most pleasant months when the rainy season over the summer-rainfall region has ended, and before the rainy season in the winter-rainfall area has begun. At this time of year, the hot summer weather has abated and the winds are lighter than during the rest of the year.
In certain areas, however, notably the hot, humid KwaZulu-Natal coast, Mpumalanga and Limpopo, June and July are the ideal holiday months.
Source: South Africa Yearbook 2010/11
Editor: D Burger. Government Communication and Information