Has Joburg skipped spring? Scientists explain why it feels like winter turned straight into summer

If it feels like Johannesburg has gone straight from a bone-chilling winter into a scorching summer, you’re not imagining it. The Daily Maverick newsroom felt it too, so we reached out to the South African Weather Service (SAWS) and meteorologists to understand what’s happening.

SAWS confirmed that, based on meteorological data, Johannesburg experienced an unusually warm period from mid-August to early September 2025.

“According to our climate data analysis, August 2025 was the fourth-warmest August in Johannesburg (OR Tambo International Airport) since 1991, with over 20 weather stations breaking new records for August countrywide,” said SAWS meteorologist Lehlohonolo Thobela.

Daytime temperatures in August were about 1.5°C above the 1991-2020 average, with nighttime temperatures 2.8°C higher than usual.

Meteorologist Michelle du Plessis, from Vox Weather, noted that across both August and September, temperatures were generally 2°C to 3.3°C warmer than expected.

 “That is quite a noticeable difference and counts as unseasonably warm for this time of year,” she said.

The first week of September was particularly striking, with daytime highs averaging 28.3°C (compared with a typical 25°C) and nighttime lows averaging 12.7°C (compared with a typical 10°C).

We haven’t skipped spring, it just feels like it

While it may feel like spring was skipped, Dr Andries Kruger, the chief scientist of climate services at SAWS, explains that seasons themselves can’t get longer or shorter. By meteorological definition, winter is June to August, and spring is September to November.

So, technically, Joburg hasn’t skipped spring – but the rapid warming creates the illusion of a shorter spring. 

“Relatively rapid warming from typical winter to typical summer temperatures can create the impression that the spring season is getting shorter,” Kruger said. This rapid warming is part of a long-term trend in South Africa’s northern provinces, where winters and springs are heating faster than other seasons, leading to milder winters and hotter springs.

“Warming over the last 30 years has also not been spatially uniform, with the northern parts of the country warming faster than the southern parts,” Kruger said. “This stronger warming in the north also shows seasonal variation, with the strongest positive trends in spring.”

And this feeling of spring shrinking, or “seasonal creep”, is being documented across the world in climate data. 

The Intergovernmental Panel on Climate Change (IPCC) confirms that spring temperatures have increased significantly, with heatwaves and high-temperature extremes appearing earlier in the season and lasting longer. In its Sixth Assessment Report the IPCC notes with high confidence that the number of warm days in spring has increased globally.

Meteorologist Du Plessis pointed to the fact that scientists at the National Oceanic and Atmospheric Administration have observed that signs of spring (such as trees growing leaves and flowers blooming) have been occurring earlier by about 2.5 days per decade, based on decades of phenological data.

Read more: How Pretoria and Joburg’s jacarandas are blooming earlier due to global heating

She also noted that the Environmental Protection Agency has found that between 1970 and 2010 the US saw its seasons shift as the climate warmed. Winters and springs heated up more quickly than summers, bringing earlier springs and stretching out warm periods in many regions. 

Why it feels so hot this spring

Dr Peter Johnston, a climate scientist at the University of Cape Town, is careful not to attribute every strange weather event we feel to climate change, but breaks down why Gauteng is feeling the heat, pointing to a mix of solar radiation, shifting weather systems and a lack of rain.

In winter, Joburg’s short days and long nights let temperatures reach the mid-20s at lunchtime, then drop sharply overnight. By September, longer days and shorter nights mean more sun and less cooling, naturally warming the city.

Normally, the Intertropical Convergence Zone – a band of moisture that brings summer storms – moves south this time of year, sparking thunderstorms over the Highveld. This year, it remains in the northern hemisphere, so clouds and rain aren’t cooling things down. “With no cloud cover, the increased sunshine is making the days much hotter,” Johnston said.

Adding to the heat, a high-pressure system is drawing hot, dry air from the Kalahari Desert across central South Africa. This “double whammy” of sun and dry air is pushing temperatures to record highs, with Johnston noting new records across the country in late August.

Read more: Only 35 of Joburg’s 60 municipal pools opened on 1 September

How (anthropogenic) climate change is influencing (natural) climate variability

Believe it or not, scientists and journalists are careful not to attribute a single hot month, or unusual weather event, simply to anthropogenic (human-induced) climate change.

Natural climate variability – the naturally occurring, short-term fluctuations in weather from one year to the next – is a powerful factor. “We do know that there is a high degree of variability, and we can’t just flatly say, oh, that’s due to climate change,” Johnston said.

Climate variability explains why one summer might be cooler and wetter, while the next is hotter and drier. These shifts are a normal part of natural processes.

But Johnston explains that climate change is shifting the baseline: “That line of average temperature is going up, and that variability (the oscillation from year to year) is sitting on the back of that line, and is therefore also increasing.”

In other words, the natural “ups and downs” are now happening on top of a rising trend, making extreme heat and other weather extremes more likely.

From what we know about anthropogenic climate change, Johnston highlights two key points. First, there is a clear long-term trend of rising global temperatures. Second, many weather extremes – such as heatwaves and heavy storms – are becoming more intense and frequent, reflecting increased atmospheric energy. This means some weather systems that were once milder are now stronger and more damaging.

SAWS meteorologist Thobela agreed with this, saying that that while August 2025’s temperature spikes could be seen as normal fluctuations, “one thing we have noticed is that weather extremes are increasing for the eastern provinces and the frequency of the extreme weather events is also increasing over the eastern regions of the country”.

The takeaway

So, what does this all mean for daily life?

“Our memories aren’t that good, and we need to actually refer to the data,” Johnston advises. While a similar hot year may have occurred in the past, we must remember that climate variability plays a strong role. 

But, seasons are now fundamentally changing because of the underlying temperature increase. And the most common consequence is an increase in extreme events.

This is especially evident in rainfall. “We are seeing massive dumps of rainfall,” Johnston said. Such heavy downpours create two major problems: South Africa’s systems – from urban drainage to agricultural infrastructure – are not built to handle them, and rising population density is worsening urban flooding. The result is a growing risk to human life, sanitation and water supply.

Du Plessis echoed this concern: “From a climate science standpoint, yes, there’s clear and measurable evidence that climate change is affecting seasonal patterns in Gauteng, with impactful consequences for future weather and water availability.”

She notes that in southern Africa, including Gauteng, climate models project shifts in rainfall patterns – meaning rain may come at different times than before – and an increase in extreme events like floods and droughts.

Research by the Centre for Environmental Rights and Greenpeace warns that South Africa’s already fragile freshwater supply will come under even greater strain as climate change increases evaporation and reduces rainfall. 

In Gauteng specifically, the Water Research Commission has found that prolonged, multiyear droughts could become more common by mid-century, threatening reservoirs, municipal supply and industry

While the Vaal Dam is currently more than 100% full, parts of west Johannesburg, including Coronationville, still face chronic water shortages, with some residents going without reliable access for more than five years, escalating to protests this week. These issues are driven by ageing infrastructure rather than drought.

Read more: ‘Scarily predictable’ — Joburg water crisis reaches boiling point as tyres burn and rubber bullets fly

Experts warn that if pipes, reservoirs and maintenance aren’t upgraded now, dry spells and future droughts will place even greater strain on the system, worsening shortages for more people.

“As the climate warms, we’re likely to see more erratic weather, with hot, dry spells, sudden storms and droughts becoming more frequent and intense,” said Du Plessis. “This will make water management in Gauteng even more challenging, affecting everything from tap water reliability to agriculture and energy production.” DM