Why some parts of South Africa are sweltering while others stay cool

South Africans can experience dramatically different temperatures depending on where they live, with one province baking under extreme heat while another enjoys considerably cooler conditions.

It is not unusual for parts of the Northern Cape, Limpopo and North West to experience very high temperatures while coastal areas or parts of the Highveld remain relatively cool.

These differences are not simply down to the time of year. South Africa’s varied landscape, altitude, surrounding oceans and changing weather systems all play a role in determining how hot or cold different parts of the country become.

Here is why temperatures can vary so significantly between provinces, sometimes on the very same day.

South Africa’s geography plays a major role

One of the biggest influences on South Africa’s temperatures is its geography.

The country has a diverse landscape that includes a high-altitude interior plateau, low-lying coastal regions, mountain ranges, semi-arid areas and subtropical lowlands.

These different environments respond to heat and changing weather conditions in different ways.

For example, the Northern Cape is characterised by large, dry areas that can experience extremely hot daytime temperatures, while the Drakensberg and other elevated regions tend to be considerably cooler.

The National Climate Change Information System (NCCIS) notes that parts of the Northern Cape can experience summer daytime temperatures exceeding 36°C, while higher-altitude areas experience much cooler conditions.

This means that even when the country is experiencing the same broad seasonal conditions, local temperatures can differ considerably.

Altitude can make some areas considerably cooler

South Africa’s interior is largely situated on a high plateau, with an average elevation of around 1 200 metres above sea level.

Higher elevations generally experience lower temperatures because air pressure decreases with altitude, causing rising air to expand and cool.

This is one reason why Johannesburg, despite being inland, does not always experience the same extreme daytime heat as lower-lying areas.

Johannesburg sits approximately 1 694 metres above sea level, while parts of the Northern Cape are considerably lower.

The Drakensberg is another example, with its highest peaks reaching more than 3 000 metres.

The altitude of the interior plateau is identified as one of the main factors responsible for the country’s relatively moderate temperatures compared with other regions at similar latitudes.

The two oceans influence coastal temperatures

South Africa is surrounded by the Atlantic and Indian oceans, which have a significant influence on temperatures along the coastline.

However, the two oceans do not affect the country in the same way.

The east coast is influenced by the warm Agulhas Current, which flows southwards along the coastline. This contributes to the warmer, more humid conditions often experienced in KwaZulu-Natal.

The west coast, meanwhile, is influenced by the cold Benguela Current, which flows northwards along the Atlantic coastline.

This helps explain why areas along the Western Cape’s west coast can experience considerably cooler conditions than parts of the east coast.

The difference is particularly noticeable in coastal towns, where the temperature of the surrounding ocean can influence local weather.

The ocean also moderates temperatures because water heats up and cools down more slowly than land.

As a result, coastal areas generally experience smaller differences between daytime and night-time temperatures than inland regions.

Cold fronts can bring a sudden temperature drop

Another reason South African provinces can experience different temperatures is the movement of weather systems.

Cold fronts regularly move in from the Atlantic Ocean, particularly affecting the Western Cape and parts of the southern coastline.

These systems can bring cooler air, increased cloud cover, rain and strong winds.

As a cold front moves eastwards, its influence can spread to other parts of the country, although not every province experiences the same conditions or temperature drop.

For example, Cape Town may experience cloudy, rainy and chilly weather while parts of Gauteng, Limpopo or Mpumalanga remain sunny and warm. The timing, strength and direction of these weather systems determine which areas are affected.

Hot berg winds can push coastal temperatures higher

While cold fronts can bring cooler weather, South Africa also experiences hot, dry winds known as berg winds.

According to the South African Weather Service (SAWS), berg winds blow from the interior plateau towards the coast.

They typically develop when a low-pressure system occurs along the coast while higher pressure is present over the interior.

As the air moves down from the elevated interior towards the coast, it is compressed and warms up.

This can cause coastal temperatures to rise sharply, sometimes resulting in extremely hot and dry conditions.

Berg winds are particularly noticeable along parts of the Western and Eastern Cape coastlines and can also increase the risk of veld fires.

Cloud cover and rainfall make a difference

The amount of cloud cover over an area can also influence how hot it becomes during the day. When skies are clear, more solar energy reaches the Earth’s surface, allowing the ground to heat up.

Thick cloud cover, on the other hand, reduces the amount of sunlight reaching the surface and can keep daytime temperatures lower.

This is one reason why an area experiencing widespread thunderstorms or persistent cloud cover may be noticeably cooler than a nearby region enjoying clear skies.

Rainfall can also contribute to cooler daytime conditions, particularly when accompanied by cloud cover and cooler air.

South Africa’s rainfall patterns differ between regions. Much of the country receives summer rainfall, while the Western Cape generally receives most of its rain during winter.

These different seasonal weather patterns also influence how temperatures vary across the country.

Why temperatures can differ within the same province

It’s important to remember that these differences are not limited to provincial borders. A province can have several distinct climate zones, meaning temperatures can vary considerably between its own regions.

KwaZulu-Natal, for example, has a warm, humid coastline, while areas further inland and towards the Drakensberg experience cooler conditions because of their elevation.

Mpumalanga also has contrasting climates. Its Lowveld is generally subtropical and warm, while the Highveld experiences colder winters and occasional frost.

The Eastern Cape has similarly varied conditions, with its coastal areas often warmer than its mountainous inland regions.

This means that a provincial weather forecast may not accurately describe conditions everywhere within that province.

Ultimately, the country’s combination of high-altitude inland areas, warm and cold ocean currents, mountain ranges and changing weather systems means that temperatures can vary dramatically from one province to another.