26 September 2023
By: Alani Janeke
Predictions indicate that significant rain may fall in the first 10 days of October over several areas that also experienced downpours over the weekend.
Predictions suggest heavy rainfall is possible in the first 10 days of October over northern parts of the southern Cape, the Garden Route, the Eastern Cape coastal area and adjacent inland areas, and southern parts of KwaZulu-Natal.
“With the development of very strong weather systems in the past week as a backdrop, there is a danger of heavy rain that could cause damage in the early part of October in these areas,” says Johan van den Berg, an independent agricultural meteorologist.
“What could increase the risk is that these areas have already received a lot of rain in the past few days, and further rain can quickly lead to flood conditions.”
Van den Berg says while light rainfall is possible over the West Coast and adjacent inland areas in the first week of October, it appears most of the rain will occur further east over the Western Cape.
Cold fronts and tropical moisture
Based on long-term forecasts, it is highly likely that further rain will fall, especially in October. It may begin over the southeastern parts of the country but is expected to shift north later.
“The major concern is that very stormy conditions can occur and expand northward. Cold fronts will continue to affect the southern parts of the country with cold air from polar regions,” says Van den Berg.
“Along with this, tropical moisture is moving southwest over Namibia and Botswana, and, as seen from September 23 to 25, it can cause very stormy conditions when the cold air and warm, moist air from the north collide.
“Cold air moves closer to the surface because it is heavier than warm air. This forces warm air to higher layers of the atmosphere where it quickly cools and condenses to form clouds and rain.”
According to Van den Berg, the higher layers of the atmosphere are still favourable for the development of cut-off low-pressure systems, leading to strong winds, hail and rain.
“This situation should change from November or December onwards when the country is expected to be more influenced by strong high-pressure systems that may limit the development of rain.”
Summer rainfall region
Regarding the summer rainfall region, short-term forecasts indicate the chance of rain will improve this week over central to eastern parts, including the eastern Free State, KwaZulu-Natal, Mpumalanga, eastern Limpopo and the entire Eastern Cape.
“This may expand further to the central to northwestern parts during the first 10 days of October. Rain is also possible over the northeastern parts of Namibia and the whole of Botswana.”
Looking further ahead, conditions during the second half of October may be more favourable for rain in the summer rainfall region, except for the western parts of the Northern Cape and the southern and southwestern parts of Namibia.
“There is a very high risk of stormy conditions and especially hail for the summer rainfall region in October and November. Very strong winds can increase the fire danger, especially when lightning begins to occur,” says Van den Berg.
