The South African Weather Service (Saws) has issued its Seasonal Climate Watch for December 2024 to April 2025, providing crucial insights into expected weather patterns across the country. South Africans can expect a hot summer with below-normal rainfall in some regions and a neutral El Niño-Southern Oscillation (ENSO) for now.
La Niña in limbo
South Africa’s summer rainfall outlook remains uncertain as the El Niño-Southern Oscillation (ENSO) is in a neutral state. ENSO, a natural climate pattern, shifts between three phases – El Niño, La Niña and ENSO-neutral – affecting global weather, including rainfall and temperatures.
Current predictions from Saws indicate that a weak La Niña could develop by mid-summer, potentially affecting South Africa’s rainfall during the latter part of the season. However, there is still considerable uncertainty about whether this shift will occur.
Professor Willem Landman, a meteorologist at the University of Pretoria and an expert in seasonal forecasts, explained that ENSO’s current neutral phase is a transitional stage between the El Niño event of 2023/2024 and the expected weak La Niña of 2024/2025. Unlike the stronger 2022/2023 La Niña event, which was predicted with high confidence, this season’s forecasts for a weak La Niña carry much less certainty.
“The presence of El Niño or La Niña allows us to make seasonal forecasts because these phases influence weather patterns. ENSO-neutral phases, like we’re in now, make predictions much harder,” Landman said.
The last ENSO event, an El Niño during the 2023/2024 summer, brought drier and hotter conditions to South Africa’s summer rainfall regions, peaking between November and January. If La Niña does develop, it could increase the likelihood of rain later in the summer, though meteorologists urge caution and continued monitoring of conditions.
Temperature forecast
It is going to be a hot summer, with both minimum and maximum temperatures likely to remain above normal across most of the country from now until April. The southern coastal regions are the exception, where below-normal temperatures are more likely throughout the season.
Rainfall predictions
The rainfall outlook for the summer rainfall regions could change, depending on if and when La Niña materialises.
But Saws’ current predictions indicate that parts of the northeastern, central and coastal areas are predicted to have above-normal rainfall.
While current predictions indicate that most parts of the summer rainfall areas are expected to receive below-normal rainfall, Saws predicted that later in summer (Feb–Apr) there is a widespread increase in chances for above-normal rainfall over the summer rainfall areas, potentially indicating a very late influence from the potential La Niña event.
Saws emphasised that these predictions may change if the ENSO predictions become more certain towards a La Niña state, and as such continued monitoring of future seasonal climate watches are advised.
Potential impacts on water and energy sectors
Saws warned that the combination of below-normal rainfall and above-normal temperatures could lead to more water losses, and lower water storage levels owing to evapotranspiration and drought.
This might have implications for water management and energy demand, with increased cooling needs expected in most parts of the country, the report said.
Associate Professor at the University of Cape Town’s Environmental and Geographical Science Department Gina Ziervogel told Daily Maverick that it is important to take the role of infrastructure into account when preparing for these weather conditions.
“For example, are the pipes and sewers functioning, is irrigation sufficient, are there cooling facilities for people if there are heatwaves, are buildings suitably constructed and [do they] have passive cooling where possible?” said Ziervogel, who is also the director of the African Climate and Development Initiative at UCT.
Ensuring these infrastructure responses are implemented takes time and planning and therefore should be urgently considered, Ziervogel said.
It is also important to consider social infrastructure. For example, considering whether education, health and social services will be able to support people in managing the impacts that are associated with these climate extremes, she said.
“Although it is important to anticipate how to respond this season, it is important to explore if more long-term adaptations can be planned and implemented, as these types of climate events are likely to occur in future, and be more frequent and intense,” Ziervogel said.
Potential impacts on health and wellbeing
- Flash floods: Above-normal rainfall predicted for most northeastern summer rainfall regions during late summer (February to April) may lead to flash floods, particularly in flood-prone areas and regions with poor drainage systems, Saws warned.
- Waterborne health concerns: The increased rainfall could result in a higher incidence of waterborne infections, water-related injuries and drowning accidents. This risk is heightened during the summer holiday season owing to increased recreational water activities, the Saws report said.
- Foodborne illness concern: Elevated temperatures might accelerate the growth of foodborne pathogens, raising the risk of foodborne illnesses. The public is advised to maintain good food hygiene and adhere to local health guidelines under these conditions. Dr Caradee Wright, lead of the Climate Change and Human Health Research Programme at the South African Medical Research Council, noted this risk is especially serious for people who do not use refrigeration, as food is likely to go bad more quickly during hot weather.
- UV exposure risk: Saws reports that above-average temperatures are predicted nationwide. Dr Wright explained that while temperature and UV are not the same, and we can’t link heatwaves to increased UV, we know that UV is highest during late spring, summer and early winter.
“We cannot feel UV – what we feel as temperature is infrared radiation. The risk of UV exposure is there even on cooler days or when it’s windy,” Dr Wright said.
Too much UV exposure, especially the kind that causes sunburn, increases the risk of skin cancer and skin damage, such as sun spots and wrinkling later in life.
The World Health Organisation says that from a UV Index of 3, we should use sun protection and avoid spending long periods of time outdoors. Most weather apps provide the UV index, but Dr Wright also suggested using your shadow – if your shadow is shorter than you, you need to use sun protection.
Precautions
Saws advises the public to take precautions and follow advice from local authorities. Local authorities are encouraged to monitor risks, develop mitigation strategies, and enhance public health surveillance.
- Advice for heatwaves: Dr Wright’s advice is to drink plenty of water; open windows early in the morning but close them before the heat of the day starts around 9am or 10am; close curtains when the sun is shining directly into a room; wet a facecloth or small towel and put it around the back of your neck and roll it occasionally to keep cool; put your hands and feet in shallow bowl of water; and, if you must be outdoors, stay in the shade wherever possible.
- Advice for UV exposure protection: Dr Wright advises wearing sunscreen, a hat, a long-sleeved cool shirt and sunglasses while outdoors and a rash vest when swimming; staying in the shade and avoiding being outdoors between 10am and 3pm for extended periods. She added that to avoid sun damage and wrinkles, it’s advisable to use a product that includes an SPF for everyday use
