Sea surface temperatures in the central Pacific Ocean (also known as the Niño regions) are on track for the development of the expected La Niña system from this week. It is expected to cross the threshold from neutral to La Niña by September.
Expected rainfall and temperatures
Johan van den Berg, an independent agricultural meteorologist, predicts the following regarding rainfall and temperatures.
Eastern summer grain production areas (KwaZulu-Natal, Mpumalanga, eastern Free State and eastern Limpopo)
The first substantial summer rains may begin from mid-October, but especially during November. This could create pressure to establish crops before the first significant rains begin.
In similar seasons in the past, such as the summers of 2016-17 and 2018-19, more than 300 mm was measured at Carolina in Mpumalanga from late October to the end of December. Very dry conditions followed. In 2018, 317 mm was recorded during the same period.
At Standerton, 450 mm fell from October to December 2016, while only 160 mm was recorded during the corresponding period in 2018. Reitz in the eastern Free State had 271 mm during this period in 2016, but only 108 mm in 2018. A drier period occurred in the second half of the season during 2017 and 2020, particularly around February and/or March.
“There is a possibility that after a good first half of the season, summer crops could suffer drought damage in the second half,” says Van den Berg.
Central to western summer grain production areas (Free State, North West, central to western Limpopo and eastern parts of the Northern Cape)
Very dry conditions or at least below-average rainfall is expected from winter to November. From the second half of November, average to above-average rainfall is expected, possibly peaking in late January and/or early February 2025.
Western parts of the Northern Cape and most of the Eastern Cape
Below-average rainfall is predicted from winter until December, with conditions for rain potentially then improving and peaking around February and March 2025. If the La Niña phenomenon is not strong enough, poor rainfall conditions may still occur in the western Kalahari and Karoo.
Regarding temperatures for the summer rainfall region, very hot conditions with possible heatwaves may occur as early as October and November. Cooler conditions may occur during the traditional hot summer period from December to February.
Production conditions
Here is an overview of the potential impact of the above weather conditions on agriculture.
Conditions in the western production area, where most of the white maize crop is produced, will be unfavourable for early plantings, with little rain and windy and hot conditions likely.
“White maize producers who produce under dryland conditions should be cautious about locking in contracts for the exceptionally good prices for delivery in March 2025,” says Van den Berg. “If good soil water conditions exist and perhaps enough planting rain falls, producers may favourably consider this.”
Summer grain producers who have increasingly begun planting soybeans in the west, but had a poor harvest during the El Niño season of 2023-24, may try soybeans again with wetter and cooler conditions expected for the 2024-25 season.
“However, consideration should be given to whether soybeans should be planted in the longer term in the warmer western production areas, with expected drier and warmer conditions predicted for the last part of this decade, from the 2025-26 season to the 2029-30 season,” says Van den Berg.
For extensive livestock farming, very dry conditions – as have already occurred since 2022 – are expected to continue in western areas, mainly including the western parts of the Kalahari, the southern parts of Namibia and the northwestern parts of the Karoo.
“Although the effect of the La Niña system is less pronounced over these areas – especially if it is a weakly developed system – the expected La Niña is likely to be reasonably strong and improve the chances for rain during the second half of the summer over these areas. However, it is important to plan for veld restoration when it rains,” says Van den Berg.
In central to western livestock areas, fairly good grazing conditions are expected from mid-summer onwards, but livestock farmers should use the expected good conditions to structurally sustain their farming operations and especially manage their livestock numbers.
