A cold spell is forecast over the western, northern and eastern regions of the Cape later this week, extending into the weekend, the South African Weather Service (Saws) says.
The weather will also lead to waves of up to 5m between Alexander Bay and Plettenberg Bay over the weekend, with strong to gale-force south-easterly winds north of Cape Point from Friday.
The forecaster said daytime temperatures for the week were expected to drop significantly from Friday into Saturday, when maximum temperatures could be below 10°C in places. Light snowfall was possible over the south-western mountains of the Western Cape as well as the southern high ground of Northern Cape on Friday afternoon into Saturday. The change in weather was expected to bring lots of rain to the areas.
Saws said cloudy to very cold weather would dominate the Northern Cape and Western Cape from Friday, spreading to include most of the Eastern Cape during the weekend.
“The rainy spell will be heralded by a cold front over the south-western part of the Western Cape by Thursday morning, with daytime temperatures dropping significantly over the southern half of South African,” the forecaster said.
There would also be widespread rainfall and snowfall over mountainous terrain. Marine gales and rough seas were expected over the southern oceanic areas.
Saws explained that upper-air troughs and cut-off lows were common over southern Africa and often brought much rain, similar to the conditions experienced during the April and May floods in KwaZulu-Natal.
“First, a well-developed upper-air trough will start nearing the Western Cape and Northern Cape from Thursday onwards, subsequently cutting off and establishing a cold core, characteristic of cut-off upper-air systems. Second, a particularly strong southern Atlantic high-pressure system is expected to extend a ridge eastward in the wake of the cold front, introducing pronounced and sustained onshore flow along the southern coastline of Western Cape as well as the Eastern Cape during the weekend.
“Moreover, the presence of coastal mountain ranges, such as the Outeniqua and Swartberg, will enhance vertical motion of air, thus enhancing the likelihood of heavy orographically-induced rainfall. It is therefore this combination or juxtaposition of surface and upper-air systems which is expected to raise the likelihood of significant, widespread and heavy rainfall, especially over the coastal mountain regions, leading to localised flooding,” Saws said.
The weather service said that given the expectation of an extended spell of cold, wet weather, as well as the possibility of snowfalls over mountainous parts of the Western Cape, Northern Cape and Eastern Cape, farmers of small stock were advised to move their animals to dry shelters at lower elevations.
“Only experienced, well-prepared hikers and climbers should venture into the mountains and hiking trails of Western and Eastern Cape this weekend. The risk of hypothermia in mountainous terrain, especially if lost, injured or ill-prepared could prove to be life-threatening,” Saws said.