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Nerd mode: every forecast, readouts, filters and range & bearing for weather enthusiasts

This week’s weatherCape Town, South Africa

Rain is likely in Cape Town on Friday

7 in 10 of NOAA’s 31 GEFS forecasts bring measurable rain to Cape Town Fri 8 a.m.–2 p.m. GMT+2.

NOAA GEFS, 31 forecasts · Mon 28 Sep 18Z run · updated Tues., Sept. 29, 1:03 a.m. GMT+2 · times are Cape Town’s (GMT+2)

See it on the globe For warnings, follow your national weather service.

Quick answers

Will it rain in Cape Town this week?
The best chances of measurable rain: Friday (7 in 10 forecasts, 8 a.m.–2 p.m.). Drier: Tue, Wed, Thu, Sat, Sun (fewer than 2 in 10 forecasts in any six hours). Times are GMT+2.
How much rain will Cape Town get this week?
By Mon., Oct. 5, 8 p.m. GMT+2 (the end of the forecast), the middle forecast has 1.1 mm of rain and melted snow, counting from Tue 2 a.m. Fewer than 1 in 10 forecasts bring 13 mm in total.
How windy will it get in Cape Town?
Gusts over 48 km/h: 5 in 10 forecasts at Sat 2 p.m. GMT+2. The middle forecast’s strongest gust is 48 km/h, Sat 8 p.m. Checked every six hours, so a brief peak can fall between.
How warm or cold will it be in Cape Town?
At the six-hourly times, the middle forecast runs from 11°C (Sun 2 a.m.) to 30°C (Wed 2 p.m.) GMT+2. The day’s real high and low can fall between those times.
Are any storms heading for Cape Town?
No storm Stormlines tracks has 1 in 10 forecasts passing its centre within 160 kilometres of Cape Town this week.

Chance of rain, six hours at a time

Tue 2–8 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneTue 8 a.m.–2 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneTue 2–8 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneTue 8 p.m.–2 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneWed 2–8 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneWed 8 a.m.–2 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneWed 2–8 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneWed 8 p.m.–2 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneThu 2–8 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneThu 8 a.m.–2 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneThu 2–8 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneThu 8 p.m.–2 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneFri 2–8 a.m.: 2 in 10 forecasts with measurable rain; middle forecast almost noneFri 8 a.m.–2 p.m.: 7 in 10 forecasts with measurable rain; middle forecast 0.5 mmFri 2–8 p.m.: 2 in 10 forecasts with measurable rain; middle forecast almost noneFri 8 p.m.–2 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneSat 2–8 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneSat 8 a.m.–2 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneSat 2–8 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneSat 8 p.m.–2 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneSun 2–8 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneSun 8 a.m.–2 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneSun 2–8 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneSun 8 p.m.–2 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneMon 2–8 a.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneMon 8 a.m.–2 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost noneMon 2–8 p.m.: fewer than 1 in 10 forecasts with measurable rain; middle forecast almost none

Each bar is the share of the 31 forecasts with measurable rain or melted snow in that six hours; the darker the bar, the more forecasts agree. Local days, GMT+2.

The week, day by day

DayChance of rain2.5 mm or moreTotal by day’s endStrongest gustTemperature
Tue 29<1 in 10<1 in 10almost none · <1 in 1019 km/h13°C–25°C
Wed 30<1 in 10<1 in 10almost none · <1 in 1016 km/h16°C–30°C
Thu 1<1 in 10<1 in 10almost none · <1 in 1045 km/h15°C–21°C
Fri 27 in 10<1 in 101.0 mm · <1 in 1032 km/h14°C–17°C
Sat 3<1 in 10<1 in 101.0 mm · <1 in 1048 km/h13°C–17°C
Sun 4<1 in 10<1 in 101.0 mm · <1 in 1022 km/h11°C–21°C
Mon 5 (part)<1 in 10<1 in 101.1 mm · <1 in 1022 km/h14°C–20°C

Chances are the highest in any six hours of the day. “Total by day’s end” is the middle forecast’s running total since Tue 2 a.m., and the share of forecasts with 13 mm or more by then; totals aren’t added up day by day, because the middle forecast of each day isn’t the same forecast. Gusts and temperatures are read every six hours.

Storms near Cape Town

No storm Stormlines tracks has 1 in 10 forecasts passing its centre near Cape Town this week. Every storm we’re tracking →

About these numbers

They come from one source, NOAA’s Global Ensemble Forecast System (GEFS): 31 runs of the same model, each started slightly differently, read at Cape Town’s coordinates on a grid about 55 km (35 miles) apart. “8 in 10 forecasts” means 8 in 10 of those runs. Nothing is adjusted for local effects such as coasts, lakes, hills or city heat, so the numbers can differ from your local official forecast, especially for snow and showers.

“Measurable rain” counts rain or melted snow in a six-hour period. Not an official forecast: follow your national weather service for warnings and decisions. How the forecasts are read: how to read the maps and the glossary.

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