Weather in Cape Town in September

How September compares

September is the 9th warmest month of the year in Cape Town and ranks 134th of 134 destinations we compare for September - see where else is hot in September. Against London's average high of 18.6°C in September, Cape Town is 0.7°C cooler by day and 0.3°C cooler at night.

Daytime and night-time in September

The typical September day in Cape Town peaks at 17.9°C, but that is an average: the warmest 10% of days reach 22.1°C or more. Roughly 1 in 31 days top 25°C and 1 in 250 pass 30°C. Nights average 10.9°C; one night in ten drops to 8.4°C or lower, so pack a layer for evenings - it is genuinely cool after dark. Between 1991 and 2020 the hottest September day here reached 32.9°C (2019-09-07) and the coldest night 5.8°C (2008-09-06).

Rain in September

Some rain (4-8 rainy days): about 8 days with 1 mm or more, 44 mm in total. Year to year it varies a lot - the wettest September was 1996 with 112 mm, the driest 1997 with 8 mm. Humidity averages 78%.

Sea temperature in September

The sea averages 14.5°C - too cold for most (under 18°c). Depending on the year it ranges from 13.8°C to 15.1°C. For the warmest sea here, come in February (18.4°C).

Sunshine and daylight

Around 6.0 hours of sunshine a day (estimated from cloud cover), 11.8 hours of daylight: the sun rises about 06:45 and sets about 18:38 local time in mid-September. Average cloud cover is 49%.

Is September a good time to visit Cape Town?

September is not the strongest month here: mild days. The best months for Cape Town on our scoring are February, January, March; months averaging 25°C or more: Jan, Feb.

Pack for mild days and cool evenings

September is a reasonable choice if you prefer being outdoors without strong heat, but it is not a reliable warm-weather upgrade from the UK. A light top may suit the warmer afternoons, while a jumper and jacket will be useful when temperatures fall. The warmer days reach around 22°C or above, but days reaching 25°C are uncommon. At the colder end, nights can fall to around 8°C or below, so pack something warmer for evenings rather than relying on summer clothes. Given the long-haul flight from London, this month makes more sense if heat is a bonus rather than the main reason for travelling.

Allow for rain, and treat the sea as cold

There is enough sunshine to make outdoor plans worthwhile, with about 6.0 hours a day, but September is not reliably dry. Around 8 rainy days mean a waterproof jacket and some flexibility are sensible; keep your outdoor plans movable rather than assuming every day will be clear. Rain need not define the whole trip, though you should be comfortable changing plans when it arrives. The sea is a separate limitation: at 14.5°C, it is cold rather than merely refreshing. If comfortable swimming is central to your holiday, September is a poor match. Time beside the water is a more realistic expectation than long, relaxed swims.