The Effect of Climate Change on South Africa’s Winter Weather Patterns

What is happening to SA’s winters and is climate change playing a significant role? Vox Meteorologist Michelle du Plessis tells us more.

Data shows that winter temperatures across southern Africa have been steadily rising since the 1960s, with fewer days of frost and freezing conditions.

According to the NOAA, extreme cold events are now far less common – and when they do happen, they’re generally milder than in the past.

In the Western Cape, where winter rainfall is vital, climate models show that the rainy season is becoming shorter and more variable.

While some winters still bring strong cold fronts and good rainfall, others are marked by long dry spells.

The WMO warns that drought risks are increasing, especially in Mediterranean-type climates like the south-western Cape.

Interestingly, while total rainfall may decrease, when storms do occur, they may be more intense – bringing short bursts of heavy rain rather than steady soaking periods. This is because warmer air holds more moisture, which can lead to more powerful frontal systems when they develop.

Recent studies suggest that mid-latitude frontal systems – the cold fronts that bring winter rain – may grow stronger under climate change. However, this doesn’t mean we’ll get more of them. Instead, we may see fewer, but more intense, winter storms, followed by longer dry periods in between.

What this means for South Africa

In short, South African winters are becoming:

  • Warmer, with fewer frost days;
  • More variable, with rain falling in short, intense bursts; and
  • Less predictable, meaning long-range planning is harder.

A Note on Snow Forecasting at Vox Weather

Some early snow forecasts recently circulated on social media suggested possible snowfall over parts of Gauteng, North West, the Highveld, and other areas that rarely experience snow during late July. At Vox Weather, we chose not to post about these projections – and here’s why.

Advanced snow forecasts, particularly more than five days ahead, are often subject to significant change. In fact, updated model guidance today NO LONGER indicates snowfall over these north-eastern regions at all.

Our approach as meteorologists to snow forecasting involves more than just looking at model snowfall outputs.

We analyse:

  • The SYNOPTIC SYSTEM expected (e.g. a cold front or cut-off low);
  • The availability and timing of PRECIPITATION; and
  • The FREEZING LEVELS (the altitude at which temperatures are cold enough for snow to form and reach the ground).

These factors must all align for snowfall to be possible. A shift in any of them can lead to significant changes in where snow may fall – or if it occurs at all.

As of the latest forecast, we see:

  • A cold front expected to move in on Friday 25 July.
  • A strong ridging high-pressure system to follow, introducing colder air over southern South Africa during the weekend of 26 and 27 July.
  • Forecast snowfall now largely restricted to the Eastern Cape, Lesotho, the southern Free State, and adjacent high-lying areas.

At Vox Weather, we prefer to wait until we see consistency in multiple forecast runs – usually within a five-day window – before communicating potential snowfall.

 

This ensures that our updates are as accurate and reliable as possible.

Snow Patrol!

The arrival of snow isn’t an everyday occurrence for most of South Africa.

As we find ourselves back in snow season, we sat down with Vox Meteorologist Michelle du Plessis to give us the lowdown on how snow is formed.

And it turns out that, for snow to fall and reach the ground, three main weather conditions must come together.

Cold air from top to bottom: The air must be below freezing (0 °C) all the way from the clouds to the ground. If there’s a warmer layer in between, the snow will melt and fall as rain or sleet. Ideal snow forms in clouds where temperatures are between -10 °C and -20 °C.

Enough moisture in the air: Cold air alone isn’t enough – you also need moisture so that water vapour can form ice crystals. Dry air, even if freezing, won’t produce snow.

Something to lift the air: Snow usually forms when air is forced to rise, cool, and condense. This can happen with cold fronts, low-pressure systems like cut-off lows, or when air is pushed up over mountains.

Gauteng’s last snowfall: July 2023…

In July 2023, Gauteng experienced rare snowfall – something locals hadn’t seen in over a decade (before 2023 it snowed in 2012 and 1996). While light snow sometimes falls in the province, heavier events like this happen only once every 10 to 20 years. So yes, it was unusual, but not unheard of.

The July 2023 cold snap wasn’t driven by climate change – instead, it was the result of a powerful cold front that swept across the entire country and extended into our neighbouring countries – supported by a steep upper-air trough, pushing icy air far north.

Looking ahead to winter 2025…

We find that the odds of another snowfall in Gauteng remain low. Climate trends suggest snow in the region will become even rarer in future. That said, nature still has surprises.

If the right weather patterns align—such as a strong cold front or cut-off low pressure system – we could see isolated snow again. But it would remain the exception, not the rule.

Climate Change and Weather Forecasting: Linking Science and People

Increased understanding helps communities prepare for extreme weather events

Climate change is affecting South Africans by significantly altering local weather patterns through higher temperatures, as well as the occurrence of extreme weather events. In fact, its impact in recent years has been so great that the government is planning to launch a national Climate Change Response Fund, which is intended to help pay for infrastructure to make South Africa more climate-resilient in the future.

This thinking reminds us of the importance of weather forecasting, both in the short term as well as over longer timeframes.

“While the planet’s climate has changed continually over the last 800,000 years through natural cycles and fluctuations, scientists have shown that human activity is driving our present spike in above normal temperatures globally,” says Vox Weather Meteorologist, Annette Botha.

“In particular, the burning of fossil fuels, such as coal, oil, gasoline and natural gas, has led to the ‘greenhouse’ effect, which is metaphorically and literally causing our planet to burn.” 

In this article, we discuss how the science of weather forecasting can provide a greater understanding of climate change, and thus help countries and communities around the world to be better prepared against the possibility of extreme weather events – as well as realising the critical importance of continuing the fight to reduce ‘greenhouse gas’ emissions.

Putting Climate Change Under the National SA Spotlight

As outlined previously, President Cyril Ramaphosa announced the implementation of the national Climate Change Response Fund (CCRF) during the February 2024 State of the Nation Address (SONA). The CCRF is intended to be a collaborative effort between the government and the private sector to fight against the increasingly devastating impacts of the climate crisis. 

During his announcement, President Ramaphosa noted the occurrence of devastating wildfires in the Western Cape, destructive floods in KwaZulu-Natal, intense heat waves in the Northern Cape, a persistent drought in the Eastern Cape and intense storms in Gauteng.

“While individual events like floods or fires cannot be solely attributed to climate change,” says Botha, “we are observing a broader trend: a steady increase in global temperatures and a rise in the frequency and intensity of extreme weather events. Climate is naturally variable, but human-driven warming is clearly shifting the baseline, making such events more likely and often more severe.”

Reduced water levels, Gamtoos Dam, Eastern Cape (Photo: The Herald)

Extreme Weather Events: Cause and Effects

Global warming has come about because of the increasing concentration of carbon dioxide (CO2) and other greenhouse gases – including water vapour, methane, nitrous oxide and fluorocarbons – that trap heat in the earth’s atmosphere and so cause a rise in global average temperatures.

Botha notes: “Because warmer air can hold more moisture, climate change results in more intense rainfall. As a result, because rainfall is increasing on average across the world, the chances of flooding are getting higher. On the other hand, climate warming also increases evaporation on land, which can worsen drought and create conditions more prone to wildfires. Added to this, the Earth’s warmer and moister atmosphere, together with warmer oceans, can create stronger hurricanes.

“Rising sea levels, which are partly caused by melting ice in the poles, increase the amount of seawater that is pushed onto shore during coastal storms, resulting in more destructive storm surges and flooding. The net result is that global warming is leading to more extreme weather events, and we have seen all of these climate change results in South Africa over the past few years.”

Lives are obviously at stake in the event of severe weather conditions if information isn’t available for warning purposes.

Botha notes: “Early warnings give people time to prepare against severe weather events like floods, tornadoes and lightning storms, whether that’s evacuating, securing property or staying indoors. Without timely updates, communities are left vulnerable, increasing the risk of damage, injuries and even loss of life.

“However, climate change is impacting on weather forecasting by altering weather patterns and increasing the frequency and intensity of extreme events, making long-term predictions more challenging.”

This is where technology comes in, to further back up the science of weather forecasting.

IBM Graf - weather forecasting via super computer

The Science and Technology of Weather Forecasting

Botha clarifies: “While short-term weather forecasts remain accurate, climate change introduces uncertainties in long-range predictions, due to shifts in climate variables like sea surface temperature and atmospheric circulation patterns. Scientists are developing new modelling techniques and tools to improve the accuracy of these long-term predictions.

“Meteorologists pull data from multiple sources including satellites, radars, weather stations and even high-altitude weather balloons. We also use global weather models and international meteorological databases. In South Africa, the South African Weather Service (SAWS) is a key provider of local weather data.”

Around the globe, high-performance computing (HPC) is crucial for weather forecasting today because it enables the efficient processing of vast amounts of data and complex mathematical models, leading to more accurate and timely predictions. HPC involves the use of multiple supercomputers to process complex and large calculations. This technology provides sufficient computational resources to improve the accuracy of short-term weather forecast systems models, with the aim of further reducing the severity of weather and climate related natural disasters. 

Linking People Through Technology

With climate change bringing more frequent and extreme weather events, platforms like Vox Weather are becoming even more important, says Botha.

“As South Africa’s first independent digital weather platform, Vox Weather delivers real-time, hyperlocal forecasts via social media and our website. We make weather updates engaging and accessible, and with close to 500,000 followers, we’re reaching more people than ever.

“We look forward to continuing to add information on climate change to our daily short-term broadcasts, as well as continuing to update our followers on the perils of climate change, and the ways in which both countries and individuals can play their role in helping to reduce greenhouse gases, in order to reduce global warming – for our future, and that of future generations,” she concludes.

Save Mother Earth... for future generations