Wetter September expected before heatwaves arrive
· Citizen
A stormy and wet start to spring, with temperatures expected to rise, with heatwaves and below-average rainfall is expected going into summer.
Vox Weather meteorologist Michelle du Plessis said spring has arrived, bringing with it a new long-term agricultural weather outlook for South Africa.
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“While parts of the country may see a wetter start to the season during September, especially across the central and eastern regions, attention is turning to the strengthening El Niño and what it could mean for the coming summer,” she said.
Stormy spring gets underway
Du Plessis said large parts of the Northern Cape and western interior experienced an exceptionally dry August, with some areas receiving only around 25% of their normal rainfall for the month, and some locations recording one of their driest winters on record.
“The winter was not only dry in many western areas, but also unusually warm,” she said.
“Analysis indicates temperatures were between 2ºC and 4ºC above normal across large parts of the Northern Cape, as well as portions of the Western Cape, North West, Free State and northern Eastern Cape.
“Several locations recorded their warmest August on record, while others experienced their warmest winter on record.”
September to bring widespread rain
The first week of September is expected to bring a sharp change in conditions, with a strong cut-off low developing over the country.
Du Plessis said seasonal guidance suggests that wetter than normal conditions may continue across parts of central and eastern South Africa during the first half of September.
Above-normal rainfall is possible over eastern parts of the country during the second week of the month, with wetter conditions continuing across sections of the central and eastern regions into the third week.
By the final week of September, the pattern becomes more mixed, with below-normal rainfall possible along parts of the south and east coasts, while wetter conditions may occur in places across Limpopo, North West, the Northern Cape, Eastern Cape and Free State.
El Niño raises heatwave concerns
South African Weather Service lead scientist Christien Engelbrecht said the expected strong El Niño of 2026-27, in combination with global warming, will likely result in 2027 being the warmest year yet recorded.
Engelbrecht said a strong El Niño event has formed in the Pacific Ocean and is likely to become a very strong event in spring.
“The latest weekly average sea surface temperature anomalies over the eastern central tropical Pacific Ocean are already exceeding the threshold that defines a very strong El Niño,” she said.
“A strong El Niño refers to an event where three-monthly averaged sea surface temperature anomalies over the eastern central tropical Pacific Ocean are exceeding 1.5ºC with respect to climatology, while during a very strong El Niño, this part of the ocean is 2ºC warmer than normal.
“The latest forecasts indicate the current event will very likely exceed the 3ºC threshold.”
Summer expected to be hotter and drier
Engelbrecht said two of the most impactful El Niño events for the southern African region are those of 1982-83 and 2015-16, which brought widespread drought.
“The very strong El Niño event of 1997-98, however, was associated with slightly above-normal rainfall over parts of South Africa’s summer rainfall region,” she said.
“It should be noted that, although below-normal rainfall is statistically the most likely outcome in southern Africa this summer, not every single El Niño event is associated with drought.”
Engelbrecht said the 2015-16 very strong El Niño event brought unprecedented heatwaves to the southern African region.
“The latest seasonal forecast of the South African Weather Service for October to December indicates below-normal rainfall is the most likely outcome over most of South Africa.
This period is also very likely to be associated with above-normal temperatures,” she said.
“The rainfall and temperature forecast for November to next January is very similar to that of the October to December 2026, with the most likely outcome for drier and warmer conditions over most of the country.”