A weather station in Blouberg, Cape Town

The station

Davis Vantage Pro2 with an integrated sensor suite. It has been running at the same site since March 2020.

A Meteobridge PRO sends readings to this server every three seconds, where the WS40 plugin shows them live and keeps a five-minute archive. Nothing goes through a third-party weather cloud; the data stays on this server.

Before WS40 the archive lived in Meteotemplate; the full history was migrated so the record is continuous from the first day.

What is measured

• Temperature and humidity — plus derived feels-like, dew point, wet-bulb and humidex.
• Wind — 10-minute average, gusts and direction; shown in knots and km/h, with Beaufort force.
• Rain — a tipping-bucket gauge gives rate and totals for today, month and year.
• Pressure — reduced to sea level, with the three-hour trend.
• Solar radiation and UV — with sunshine hours estimated from radiation.

Not from the station

The forecast, air quality and sea conditions come from Open-Meteo‘s models; the tide chart is published daily by the South African Weather Service. They are labelled as such on the page.

Blouberg’s climate, from this archive

Blouberg has a Mediterranean climate: warm, dry, windy summers and mild, wet winters. The numbers below are calculated from this station’s own records and update as the archive grows.

• Average rainfall is about — a year, most of it between May and August. The wettest month on average is — (—), the driest — (—).
• The warmest month is —, averaging — with typical afternoon highs near —; the coolest is —, averaging — with nights around —.
• The hottest reading so far was — on —; the coldest — on —.
• The strongest gust recorded was — on —; the wettest single day brought — on —.

Summer is dominated by the south-easter — the “Cape Doctor” — which funnels around Table Mountain and blows hardest in the afternoons from November to February. Winter brings north-westerly cold fronts off the Atlantic, which deliver almost all of the year’s rain and the biggest swells. The sea stays cold all year because the Benguela current carries water up from the Southern Ocean; summer upwelling can push sea temperatures below 12 °C even on the hottest days.

About Blouberg

Bloubergstrand — “blue mountain beach” in Afrikaans, named for the hill behind it — sits on Table Bay about 15 km north of Cape Town’s city centre. Its beach has the classic postcard view of Table Mountain across the water, with Robben Island to the west. The coast here runs north through Table View, Big Bay and Melkbosstrand, backed by the Blaauwberg Nature Reserve.

The steady south-easter and shallow, sandy shoreline make Blouberg one of the best-known kitesurfing and windsurfing spots in the world; on a summer afternoon Kite Beach and Dolphin Beach are full of sails. The same wind and sea shape everyday life here: beach walks, sunsets over the Atlantic, surfing at Big Bay, and the annual arrival of the first winter swells.

The area’s history runs deep: the Battle of Blaauwberg was fought on these slopes in January 1806, when British forces landed at Losperd’s Bay (now Melkbosstrand) and took the Cape from the Dutch Batavian Republic.

Reading the numbers

Feels like

Air temperature adjusted for wind chill (cold, windy) or humidity (hot, humid).

Dew point

The temperature at which the air would be saturated. Above 18 °C feels muggy; below 10 °C feels dry.

Wind and gust

Wind is the 10-minute average; gust is the highest few-second peak within it. Kiters read knots; 1 kn = 1.852 km/h.

Beaufort

The 0–12 force scale: 4 is a moderate breeze (11–16 kn), 6 a strong breeze (22–27 kn), 8 a gale (34–40 kn).

Pressure trend

The change over three hours. A fall of more than 3 hPa usually means a front is coming.

UV index

0–2 low, 3–5 moderate, 6–7 high, 8–10 very high, 11+ extreme. Cape Town summers routinely reach 11+.

Cloud base

Estimated height at which cumulus would form, from the gap between temperature and dew point.

Humidex

A Canadian comfort index combining heat and humidity; above 30 is uncomfortable, above 40 dangerous.

Records vs. daily means

The Records page’s extremes are single readings; its monthly and yearly tables use daily means, which is why they differ.