Understanding the weather in South Africa – Part 1

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At any time there are many weather systems weaving around the globe, however when averaged over many years a global pattern of air movement emerges.

The reason we have different weather patterns, jet streams, deserts and prevailing winds is all because of the global atmospheric circulation caused by the rotation of the Earth and the amount of heat different parts of the globe receive.

Over the major parts of the Earth’s surface there are large-scale wind circulations present. The global circulation can be described as the world-wide system of winds by which the necessary transport of heat from tropical to polar latitudes is accomplished. Global Circulations explain how air and storm systems travel over the Earth’s surface.

The earth’s tilt, rotation and land/sea distribution affect the global weather patterns we observe. While the weather varies from day-to-day at any particular location, over the years, the same type of weather will reoccur. The reoccurring “average weather” found in any particular place is called climate.

German climatologist and amateur botanist Wladimir Köppen (1846-1940) divided the world’s climates into categories based upon general temperature profile related to latitude. He worked with Rudolf Geiger to modify these categories which is known today as the Köppen-Geiger climate classification system.

Köppen was trained as a plant physiologist and realized that plants are indicators for many climatic elements. His effective classification was constructed on the basis of five vegetation groups determined by the French botanist De Candolle referring to the climate zones of the ancient Greeks. The five vegetation groups of Köppen distinguish between plants of the equatorial zone (A), the arid zone (B), the warm temperate zone (C), the snow zone (D) and the polar zone (E).

A second letter in the classification considers the precipitation (e.g. Df for snow and fully humid), a third letter the air temperature (e.g. Dfc for snow, fully humid with cool summer)

First letter

  • A – equatorial zone
  • B – arid zone
  • C – warm temperate zone
  • D – snow zone
  • E – polar zone

Second letter

  • f – wet year-round
  • s – dry summer season
  • w – dry winter season
  • m – monsoon

Third letter

  • a – hot summer
  • b – warm summer
  • c – cool summer
  • d – very cold winters

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The climate of SA can be divided into three regions according to Koppen-Gieger climate classification with the climate zones shown in red, orange and green colors

  1. Equatorial savannah with dry winters
  2. Arid climates
  3. Warm temperate climates

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Koppen-Gieger climate classification of South Africa representing different climatic regions (Source: – geiger.vu-wien.ac.at/)

Aw: Equatorial savannah with dry winter

Winter dry season. There are more than two months with less than 60mm of precipitation in winter.

Sodwana Bay, Tembe Elephant Safaris, Kosi Bay Rest Camp, Mabibi Campsite, Thonga Beach Lodge


BWk: Cold desert climate

Cold deserts have a mean annual temperature of less than 18 °C and no more than 200mm of precipitation annually.

Cold desert climates usually feature hot (or warm in a few instances), dry summers, though summers are not typically as hot as hot desert climates. Unlike hot desert climates, cold desert climates tend to feature cold, dry winters.

Beaufort West, Victoria West, Calvinia, Port Nolloth, Touws River


BWh: Hot deserts climate

Hot desert have a mean annual temperature of at least 18 °C and no more than 200mm of precipitation annually.

These climates usually feature hot, sometimes exceptionally hot, periods of the year. In many locations featuring a hot desert climate, maximum temperatures of over 40 °C (104 °F) are not uncommon in summer and can soar to over 45 °C (113 °F) in the hottest regions.

Klawer, Vredendal, Vanrhynsdorp, Musina, Keimoes


BSk: Cold semi-arid (steppe)

Steppe climates are intermediates between desert climates (BW) and humid climates in ecological characteristics and agricultural potential.

To determine if a location has a semi-arid climate, the precipitation threshold must first be determined. Finding the precipitation threshold (in millimeters) involves first multiplying the average annual temperature in °C by 20, then adding 280 if 70% or more of the total precipitation is in the high-sun half of the year (April through September in the Northern temperate zone, or October through March in the Southern), or 140 if 30%–70% of the total precipitation is received during the applicable period, or 0 if less than 30% of the total precipitation is so received. If the area’s annual precipitation is less than the threshold but more than half the threshold, it is classified as a BS (steppe climate).

Cold semi-arid climates have a mean annual temperature below 18°C, or a mean temperature of no more than 0°C in the coldest month.

Bloemfontein, Mossel Bay, New Bethesda, Jacobsbaai, Paternoster

BSh: Hot semi-arid (steppe)

Hot semi-arid climates have a mean annual temperature of at least 18°C, or a mean temperature greater than 0°C in the coldest month.

Madikwe Safari Lodge, Clanwilliam, White City, Saldanha, Uitenhage

Cfa: Humid subtropical

Temperate, without dry season, hot summer.

With the coldest month averaging above 0 °C (32 °F), at least one month’s average temperature above 22 °C (71.6 °F), and at least four months averaging above 10 °C (50 °F).

No significant precipitation difference between seasons. No dry months in the summer.

Durban, Pretoria, Kanyamazane, eMankayana, Matsulu

Cfb: Temperate oceanic

Temperate, without dry season, warm summer.

Coldest month averaging above 0 °C (32 °F), all months with average temperatures below 22 °C (71.6 °F), and at least four months averaging above 10 °C (50 °F).

No significant precipitation difference between seasons.

Johannesburg, Soweto, Port Elizabeth, Roodepoort, Krugersdorp


Csa: Hot-summer Mediterranean

Temperate, dry hot summer.

The coldest month averaging above 0 °C (32 °F), at least one month’s average temperature above 22 °C (71.6 °F), and at least four months averaging above 10 °C (50 °F).

At least three times as much precipitation in the wettest month of winter as in the driest month of summer, and driest month of summer receives less than 30 mm (1.2 in).

Klapmuts, Groot-Drakenstein, Simondium, Paarl, Windmeul

Csb: Warm-summer Mediterranean

Temperate, dry warm summer

The coldest month averaging above 0 °C (32 °F), all months with average temperatures below 22 °C (71.6 °F), and at least four months averaging above 10 °C (50 °F).

At least three times as much precipitation in the wettest month of winter as in the driest month of summer, and driest month of summer receives less than 30 mm (1.2 in).

Cape Town, Mitchells Plain, Blue Downs, Bellville, Elsiesrivier


Cwa: Monsoon-influenced humid subtropical

Temperate, dry winter, hot summer.

The coldest month averaging above 0 °C (32 °F), at least one month’s average temperature above 22 °C (71.6 °F), and at least four months averaging above 10 °C (50 °F).

At least ten times as much rain in the wettest month of summer as in the driest month of winter (an alternative definition is 70% or more of average annual precipitation is received in the warmest six months).

Ifafi, Makweti, Mothutlung, Mmakau, Mapetla

Cwb: Subtropical highland or temperate oceanic with dry winters

Temperate, dry winter, warm summer.

The coldest month averaging above 0 °C (32 °F), all months with average temperatures below 22 °C (71.6 °F), and at least four months averaging above 10 °C (50 °F).

At least ten times as much rain in the wettest month of summer as in the driest month of winter (an alternative definition is 70% or more of average annual precipitation received in the warmest six months).

Randburg, Irene, Alexandra, Sandton, Ermelo

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CWb: The Amphitheatre, Drakensberg Mountains (Uthukela District, KwaZulu-Natal, South Africa)

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BSh: View of the old pit (Doornhoek Mine, Ngaka Modiri Molema District, North West, South Africa)

Geography of South Africa

South Africa is located at the southernmost region of Africa, with a long coastline that stretches more than 2,500 km and along two oceans: the South Atlantic and the Indian). At 1,219,912 km2, according to the UN Demographic Yearbook, South Africa is the 24th-largest country in the world. It is about the same size as Colombia, twice the size of France, three times as big as Japan, four times the size of Italy and five times the size of the United Kingdom.

Mafadi in the Drakensberg at 3,450 m is the highest peak in South Africa. Excluding the Prince Edward Islands, the country lies between latitudes 22° and 35°S, and longitudes 16° and 33°E.

The interior of South Africa consists of a vast, in most places almost flat, plateau with an altitude of between 1,000 m and 2,100 m, highest in the east and sloping gently downwards towards the west and north, and slightly less noticeably so to the south and south-west. This plateau is surrounded by the Great Escarpment whose eastern, and highest, stretch is known as the Drakensberg.

The south and south-western parts of the plateau (at approximately 1,100–1,800 m above sea level), and the adjoining plain below (at approximately 700–800 m above sea level) is known as the Great Karoo, which consists of sparsely populated scrubland.

To the north, the Great Karoo fades into the even drier and more arid Bushmanland, which eventually becomes the Kalahari desert in the very north-west of the country.

The mid-eastern, and highest part of the plateau is known as the Highveld. This relatively well-watered area is home to a great proportion of the country’s commercial farmlands and contains its largest conurbation (Gauteng). To the north of Highveld, from about the 25° 30′ S line of latitude, the plateau slopes downwards into the Bushveld, which ultimately gives way to the Limpopo lowlands or Lowveld.

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Prevailing macroclimatic conditions in South Africa

South Africa’s climatic conditions generally range from Mediterranean in the southwestern corner of South Africa to temperate in the interior plateau, and subtropical in the northeast. A small area in the northwest has a desert climate. Most of the country has warm, sunny days and cool nights. Rainfall generally occurs during summer (November through March), although in the southwest, around Cape Town, rainfall occurs in winter (June to August). Temperatures are influenced by variations in elevation, terrain, and ocean currents more than latitude.

Temperature and rainfall patterns vary in response to the movement of a high pressure belt that circles the globe between 25º and 30º south latitude during the winter and low-pressure systems that occur during summer. There is very little difference in average temperatures from south to north, however, in part because the inland plateau rises slightly in the northeast. For example, the average annual temperature in Cape Town is 17ºC, and in Pretoria, 17.5ºC, although these cities are separated by almost ten degrees of latitude. Maximum temperatures often exceed 32ºC in the summer, and reach 38ºC in some areas of the far north. The country’s highest recorded temperatures, close to 48ºC, have occurred in both the Northern Cape and Mpumalanga.

Frost occurs in high altitudes during the winter months. The coldest temperatures have been recorded about 250 kilometers northeast of Cape Town, where the average annual minimum temperature is -6.1º C. Record snowfalls (almost fifty centimeters) occurred in July 1994 in mountainous areas bordering Lesotho.

Climatic conditions vary noticeably between east and west, largely in response to the warm Agulhas ocean current, which sweeps southward along the Indian Ocean coastline in the east for several months of the year, and the cold Benguela current, which sweeps northward along the Atlantic Ocean coastline in the west. Air temperatures in Durban, on the Indian Ocean, average nearly 6º C warmer than temperatures at the same latitude on the Atlantic Ocean coast. The effects of these two currents can be seen even at the narrow peninsula of the Cape of Good Hope, where water temperatures average 4º C higher on the east side than on the west.

Rainfall varies considerably from west to east. In the northwest, annual rainfall often remains below 200 millimeters. Much of the eastern Highveld, in contrast, receives 500 millimeters to 900 millimeters of rainfall per year; occasionally, rainfall there exceeds 2,000 millimeters. A large area of the center of the country receives about 400 millimeters of rain, on average, and there are wide variations closer to the coast. The 400-millimeter “rainfall line” has been significant because land east of the rainfall line is generally suitable for growing crops, and land west of the rainfall line, only for livestock grazing or crop cultivation on irrigated land.

South African Weather By Province

Overall, the Western Cape climate is typically Mediterranean, with warm, dry summers and mild, moist winters and low summer rainfall prevail. Near the coast, summer’s temperature rises from a pleasant low of 15º C to a heartwarming 27º C. Inland temperatures are some 3-5º C higher. Coastal winters see the mercury dropping to a mild 7º C at night and rising to a comfortable 18º C by day. Away from the beach, morning wakens to an invigorating 5º C and midday peaks at 22º C.

The Garden Route region has a Mediterranean Maritime climate, with moderately hot summers, and mild to chilly winters. It is one of the richest rainfall areas in South Africa. Most of the rains occurs in the winter months, brought on by the humid sea-winds from the Indian ocean.

The coastal area of the Eastern Cape Province lies directly between the subtropical conditions of KwaZulu Natal and the Mediterranean conditions of the Western Cape, while its inland area is bisected by the great escarpment resulting in the southern reaches defined by a series of rivers and corresponding wetland fauna and flora, while the northern areas are those of the altitudinous plains of the Plateau and great Karoo. These topographical differences are what cause the climatic differences and conditions experienced by the towns and cities within these areas.

The climate in the KwaZulu Natal Province is all year ’round tourist friendly. Sea temperatures are also relatively stable, averaging 21 degrees all year, providing possibilities for a diversity of aquatic activities in any season, including diving, fishing, swimming, boating and surfing.

The Gauteng Climate is said to offer one of the world’s best climates: summer days are warm and wind free and winter days are crisp and clear. Johannesburg and Pretoria differ in temperature by about 2% (Pretoria being the warmer of the two).

Mpumalanga’s weather is naturally defined by its topography. Mpumalanga is a province of two halves, namely the high-lying grassland savannah of the highveld escarpment and the subtropical Lowveld plains. The western side of Mpumalanga, on the highveld escarpment, is like a rise of tropics, an ascent into an uncompromising range of temperatures. The west is drier, hotter and much colder than the rest of the Mpumalanga province.

Finding itself at South Africa’s northernmost area and bisected by the tropic of Capricorn, visitors to Limpopo can expect sunshine, long summer afternoons and dry days for most of their stay. Polokwane (previously known as Pietersburg), the capital city of Limpopo, lies more or less in the centre of the Limpopo province and its weather is reflective of most of it. Only the region east of the city offers markedly different climate, with most the subtropical conditions of the Lowveld providing weather more suited to dense forests.

Forming the southern part of the Kalahari Desert the North West Province offers almost year-round sunshine, making suntan lotion and a hat a prerequisite when visiting the North West Province, South Africa. The capital city, Mafikeng, enjoys weather indicative of largely the entire North West Province, with towns in the western areas only slightly hotter and those further south a bit cooler.

The Free State Province, with its vast beauty, endures a fair amount of hardship due to it’s hot, arid climate. Almost uniformly at about 1,300m above sea level, the Free State has weather typical of an interior plateau with summer rains, chilly winters and plenty of sunshine. To the north, the Vaal irrigation area nourishes the small assortment of farming towns below it, and the hue of the Free State countryside is often green.

Although the Northern Cape Province is mainly semi desert, the western areas of the Northern Cape, including Namaqualand, a small section of the Green Kalahari and Calvinia, Nieuwoudville and Loeriesfontein in the Upper Karoo fall into the winter rainfall area from April to September.

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