Water conservation will be key in Stellenbosch in the coming months as the impact of the strengthening El Niño is being felt. This is according to Peter Johnston, an independent climatologist, who says that the unusually dry July has coincided with the strengthening El Niño.
“We can’t guarantee a drier-than-normal situation for the rest of winter, but we can confidently say the coming summer will be hotter than normal,” said Johnston.
While the impact of the current El Niño is expected to be milder in Stellenbosch than in other parts of the country, Stellenbosch can expect below average rainfall heading into spring, said Neville Sweijd, an associate professor in climate studies at Stellenbosch University (SU).
A dry, bright overcast sky hangs over the bare winter trees on Victoria Street, Stellenbosch. PHOTO: Hae-Won Boesack
Lower rainfall combined with higher evaporation and reduced soil moisture puts pressure on the Stellenbosch region heading into summer, said Johnston.
Theewaterskloof Dam is Stellenbosch’s biggest water source in the Overberg region according to the department of water and sanitation (DWS).
In July this dam stood at 78.4%; marginally ahead of the 78.2% recorded at the same time last year, according to DWS. Despite the relatively high level, the dam received far less rainfall than usual. Typically the dam recorded 65mm of rain in July, but this year, only 13mm was recorded by the DWS.
Another water source, Berg River, sits at 89% capacity, compared to the 100% at the same time last year according to the DWS.
Warmer temperatures in line with climate change
Although the current El Niño is strengthening, warmer temperatures are “in line with climate change scenarios and projected impacts. Global temperatures are increasing, causing a more unstable atmosphere, bringing more frequent extreme rainfall events,” said Johnston. Climate change also contributes to longer dry spells and higher temperatures between storms.
El Niño is the warm phase of a natural cycle called the El Niño-Southern Oscillation (ENSO) in which the Central Pacific Ocean periodically warms and shifts rainfall and temperature patterns globally, according to Sweijd.
video
Stellenbosch has been warmer and drier than usual during July. Neville Sweijd, an associate professor in climate studies at Stellenbosch University, weighs in on El Niño and what it means for Stellenbosch. VIDEO: Hae-Won Boesack
The El Niño’s impact is expected to hit hardest in the interior highveld and northern parts of the country, said Lehlohonolo Thobela, meteorologist and weather forecaster at the SAWS.
Because the Western Cape experiences warm and dry summers, “the effect on rainfall in the Western Cape [in summer] is marginal, if anything at all,” said Sweijd.
Stellenbosch’s weather has swung between extremes in the past few years, including major flooding in 2023 and 2024, according to SAWS. In May this year, Stellenbosch experienced one major flood followed by a dry spell, said Sweijd.
Although weather patterns can still shift over the coming weeks, Sweijd said the broader climate change trend shows a warmer spring and summer. This makes water conservation increasingly important if below-average rainfall continues.
Average annual surface temperature trends for South Africa from 1901 to 2025. Data reveals a steady increase signalling a clear warming trend. INFOGRAPHIC: Hae-Won Boesack (Source: Climate Change Knowledge Portal)
“There are many different mechanisms that bring rainfall, but the bottom line is that if the cold fronts carrying the rain don’t move far enough north, they miss us,” said Sweijd about current rainfall figures.
Meanwhile, Sweijd has warned that weather forecasts only become more accurate a few days in advance. “We can’t predict [the weather] with real accuracy two weeks or a month out.”