By Alani Janeke
More rain is forecast for parts of the country in the coming weeks, but the chances of excessively wet conditions during this year’s harvest time are slim.
The likelihood of further good rainfall within the next four weeks over the western parts of the Northern Cape is poor. Good rains have occurred in the area over the past two weeks, though some spots only received a few millimetres.
“Rain may occur again during winter with the arrival of strong cold fronts in these regions, although long-term forecasts indicate a below-average chance of rain over the western parts in winter and spring,” says Johan van den Berg, an independent agricultural meteorologist.
“Additional rain will continue to fall in the eastern and southeastern Northern Cape, the whole Eastern Cape, and the remaining regions that receive summer rainfall until at least the second half of April. The rainfall is expected to be light, except on March 26 and 27 when more than 20 mm of rain is forecast, particularly in the Free State, Eastern Cape, Gauteng, Mpumalanga, and parts of KwaZulu-Natal.”
He mentions that since the La Niña phenomenon shifted to neutral conditions by the end of February this year, its positive effect on summer rainfall will also decrease. “Traditionally, stronger La Niña events can positively influence rainfall until May, but this is not expected to happen this year. Therefore, the risk of excessively wet conditions during harvesting is low.”
According to Van den Berg, early plantings of summer grains that reach harvest readiness by the second half of April may face challenges due to wet and humid conditions. These conditions could also complicate the baling of fodder.
Winter rainfall region
As for rain in the winter rainfall region, light precipitation is forecast for 24 and 25 March and the first and third weeks of April. Less than 10mm is expected.
“Given the high temperatures currently experienced in some areas, this rain is likely to be ineffective. The true winter rainfall season, typically associated with cold fronts, is expected to begin only in the latter half of May or possibly even June.”
“There is considerable concern about the possibility of below-average rainfall during the winter rainy season, which would affect the levels of storage dams,” says Van den Berg. “Current weather forecasts indicate that the West Coast and western regions of the Western Cape, including the Swartland, will receive less rain than the Southern Cape.”
Low temperatures and frost
Low temperatures and frost are now the most significant risks for summer grain harvest after sufficient rains counteracted drought damage in some areas. A lack of heat due to cloudy conditions and low daytime temperatures is now a significant issue. In Standerton, Mpumalanga—one of the areas where planting was done very late—forecasts show that at least 15 days with maximum temperatures below 25°C will occur until 15 April. At least 12 of those days will also be cloudy.
Limited sunshine and low maximum temperatures can lead to below-average kernel mass, possibly resulting in harvest losses,” says Van den Berg.
Widespread frost only in May
The general trend indicates that the first frost date has been postponed by approximately two weeks. The highly humid conditions experienced in parts of the summer rainfall region may help to prevent frost from occurring too early.
In cooler areas such as the southern Free State, high-altitude regions of the Eastern Cape, and nearby locations, minimum temperatures may drop below 5°C in the first week of April, though severe frost is not expected. Additional rain and humid conditions could help minimise frost damage. By the last week of April, minimum temperatures in these colder areas may approach 0°C, with large-scale frost anticipated only in May.
Van den Berg says a lack of heat and very cloudy conditions over the next three weeks could slow the growth of summer grains.
