Western Cape Geography & Climate

The Western Cape is shaped by an ancient folded mountain system and by the meeting of two very different oceans.

Table Mountain

A flat-topped massif of hard Table Mountain sandstone laid down some 500 million years ago over a much older granite and shale base, rising to 1,086 metres directly above the city. The flatness is an erosion surface, not a volcanic feature. The tablecloth cloud forms when moist south-easterly air is forced up the slope and condenses, then evaporates as it spills over the front.

The Cape Fold Belt

Parallel sandstone ranges — the Hottentots Holland, Langeberg, Swartberg and Cederberg — folded around 250 million years ago and eroded into dramatic ridges, separated by fertile valleys where the wine and fruit are grown.

Two oceans

The cold Benguela current runs up the Atlantic side and the warmer Agulhas down the Indian Ocean side; they meet roughly at Cape Agulhas, the true southern tip of Africa, not the Cape of Good Hope. The temperature difference between beaches a few kilometres apart across the peninsula is dramatic — around 12°C on one side and 20°C on the other.

Fynbos

The Cape Floral Kingdom is the smallest and richest of the world’s six floral kingdoms, with around 9,000 plant species of which roughly 70 per cent grow nowhere else. Table Mountain alone holds more species than the whole of Britain. It is UNESCO-listed and fire-dependent — many species need smoke or heat to germinate.

The interior

Behind the mountains lies the Karoo, a semi-desert of enormous horizons and some of the darkest night skies anywhere.

The Western Cape has a Mediterranean climate — the only part of South Africa that does — with rain in winter rather than summer.

Summer

November to March is warm and dry, with Cape Town averaging 16 to 26°C and inland valleys considerably hotter — Robertson and the Karoo regularly exceed 35°C. It barely rains for months.

The Cape Doctor

The summer south-easterly wind is a defining feature. It blows hard and for days at a time, lays the tablecloth cloud over the mountain, clears the air — hence the nickname — and makes the Atlantic beaches unusable while leaving False Bay calm. Wind, not rain, is what actually spoils summer days here.

Winter

June to August brings cold fronts off the Atlantic: 8 to 18°C, rain, and sometimes serious storms. Snow falls on the high mountains. Between fronts, winter days can be still and brilliantly clear.

Rain shadow

Rainfall drops sharply moving inland — over a metre on the mountain slopes, under 200 millimetres in the Karoo within a couple of hundred kilometres.

Drought and fire

The 2015-2018 drought took Cape Town close to shutting off its municipal supply, and the region remains water-stressed. Summer brings serious fynbos fires, and hiking closures on high-risk days are enforced.

Microclimates

The mountains chop the province into pockets that behave quite differently. Constantia on the wet eastern slope gets roughly twice the rain of the city bowl a few kilometres away; Hout Bay is sheltered when Camps Bay is unusable; and the Hemel-en-Aarde valley is cool enough for Pinot Noir while Robertson, an hour further inland, is baking. Checking the forecast for the specific valley, not the province, is worth doing.

Sea temperature

The Atlantic side stays around 12 to 15°C all year; False Bay reaches 20°C or more in summer.