23 January 2024
Average to below-average rainfall may persist until early February, particularly over central and western parts of the country, while more regular rainfall is possible over eastern parts.
The areas where regular rain could occur include the Free State, Mpumalanga and KwaZulu-Natal.
There are no active tropical cyclones but the tropical low-pressure system just east of Madagascar is expected to strengthen in the next week, with air pressure dropping and more rainfall stimulated due to moist air moving southward over the Indian Ocean.
“This will cause less rain over central to western parts of southern Africa with further rain over eastern parts of the summer rainfall region, especially KwaZulu-Natal,” says Johan van den Berg, an independent agricultural meteorologist.
More tropical moisture may still occur over far eastern parts of the country during this period, and with the movement of a high-pressure system past the Cape, cold air could be displaced northward along the east coast.
“Where the cold and warm air meet, very stormy conditions occur,” says Van den Berg. “This is also the reason for the heavy rain, hail and wind in parts of KwaZulu-Natal recently, as well as the sporadic sharp temperature drops in recent weeks. The Drakensberg in this area creates further favourable conditions for stormy conditions where these two air masses meet.”
High temperatures
In the coming weeks, temperatures will remain fairly high over central to western and northern inland areas. For the western inland, in Upington for example, maximum temperatures will mainly stay above 35°C until at least the end of February. Temperatures will also remain high in the summer grain area, with Bothaville experiencing temperatures above 30°C for most of the rest of January and February.
Van den Berg says predictions show it will be warm to very warm in western production areas such as Schweizer Reneke, Delareyville and Vryburg until mid-February. “In eastern production areas, such as the eastern Free State, KwaZulu-Natal and Mpumalanga, maximum temperatures will be more moderate for most of the next few weeks at 25°C to 30°C.”
As for the winter rainfall region, very little rain is expected until at least mid-February. “Very high temperatures will occur over the central to western inland areas of the Western Cape, which may persist into the second half of February.”
State of summer crops
Upington in the Northern Cape recorded only a few days with maximum temperatures lower than 35°C from January 1 to 21. “Although heavy rainfall with flood conditions occurred in some areas, especially KwaZulu-Natal and even Limpopo, very little rain occurred over the rest of the country,” says Van den Berg.
“Agricultural conditions generally look average to above average although there are areas, especially in the Northern Cape, where conditions of drought disaster prevail.
“Another cause for concern is the large number of late plantings, especially of maize, in western production areas. These plantings will come into seed only by the second half of February, and the next at least six weeks will be crucial in terms of rainfall.”
Water consumption of maize sharply increases from 40 days after planting, with maize using up to 30% of its seasonal consumption for a season until then. “There is still a very large water need until mid-March.” After that, water consumption will start to decrease.
“Fortunately, there is relatively abundant carry-over groundwater this year, and the rain in the last part of December and the first part of January has also contributed to favourable groundwater conditions.
“Given the total water requirement of maize that must yield 5-8 tons per hectare, at least another 250-400 mm of water must be available as rain or groundwater from now until the maize is mature,” says Van den Berg.
