A cold front could cause minimum temperatures below freezing over high-altitude parts of the Western Cape and the southern parts of the Northern Cape next week.
By Alani Janeke, Senior Journalist at African Farming and Landbouweekblad
The start of spring has begun with maximum temperatures of up to 30°C in some parts of the country. Berg wind conditions are occurring in parts of the Southern Cape and Klein Karoo today, in places such as Swellendam, Riversdale, Oudtshoorn and Calitzdorp.
“Berg wind conditions occur when the flow of air flows from the interior, with warm winds blowing from a north-westerly to westerly direction to a south-easterly or easterly direction, like today. The wind is warm because it blows for a long distance over the dry and warm interior,” explains Johan van den Berg, independent agricultural meteorologist.
Chances of late frost?
Although minimum temperatures of below 5°C are still occurring across the central to southern interior, sharp temperature drops that could cause heavy frost are not forecast for the next week.
Van den Berg says the big question remains, however, whether cold conditions that could cause frost damage could still occur later in the season? In recent years, frost has occurred very late in the season across the central to southern interior until at least the end of September, sometimes even well into October.
Areas where frost can occur late are mainly the Free State, the Mpumalanga Highveld, the southern parts of the Northern Cape, the interior of the Eastern Cape and the interior of the Western Cape (which includes the Winelands district, the Karoo and even parts of the Southern Cape).
As a cold front moves in over the west coast next week, minimum temperatures as low as -2°C could occur at Ceres and Barrydale in the Western Cape around 13 September. Over the southern parts of the Northern Cape, in places like Sutherland, minimum temperatures could also drop to -2°C around 13 September.
“These cold conditions are not expected to move too far north, with very low temperatures not expected along the Orange River’s important grape growing areas or further north, for example,” explains Van den Berg.
Cold fronts are currently passing south of the country, but Van den Berg says that as has happened in the past, this trend can change quickly.
“Although there have been a few years in the past where frost has stopped early, this has been the exception. The likelihood that frost could still occur in Limpopo, the northern parts of the North West as well as over the northern parts of KwaZulu-Natal is very small.”
Forecasts indicate that weak frontal systems could move across the country around 4 September, 9 and 10 September, 12 and 13 September, 16 and 17 September, 20 and 21 September, 28 and 29 September, as well as at the end of the first week of October.
“Although these systems are currently indicated as weak, it is well ahead of time and conditions can change rapidly in the coming weeks.”
More winter rain?
Van den Berg says that although the predicted frontal systems can cause rain, the precipitation is indicated as light. Significant rain is predicted for around 12 and 13 September, with 10mm or more falling over fairly large areas from the Swartland to across the Southern Cape at approximately George.
Very little winter rain is expected during the second part of September as well as October.
