Yes

you do need a jacket based on the weather in Blue Downs, Cape Town, South Africa 1 second ago

Why? Because it's cool. Pleasantly cool, but cool!
53°F11°C & Clear

Wind is 3 mph5 km/h from the Southeast, gusting to 8 mph13 km/h
September 8
12am53°F11°C3 mph5 km/h SoutheastClear
1am52°F11°C3 mph5 km/h EastMostly Clear
2am55°F13°C3 mph5 km/h NortheastMostly Clear
3am60°F15°C3 mph4 km/h SouthClear
4am65°F18°C3 mph5 km/h SouthwestClear
5am69°F21°C3 mph5 km/h SouthwestClear
6am73°F23°C3 mph6 km/h SouthwestClear
7am76°F25°C4 mph6 km/h SouthwestClear
8am79°F26°C5 mph7 km/h SouthwestClear
9am80°F27°C5 mph8 km/h SouthClear
10am81°F27°C5 mph7 km/h SouthClear
11am80°F27°C4 mph6 km/h SouthClear
DateLowHighWindDayNight
September 752°F11°C81°F27°C4 mph6 km/h from SouthClearClear
September 856°F13°C78°F26°C7 mph11 km/h from NorthClearPartly Cloudy
September 956°F13°C73°F23°C4 mph6 km/h from WestPartly CloudyMostly Cloudy
September 1056°F13°C69°F20°C7 mph11 km/h from SouthPartly CloudyMostly Clear
September 1155°F13°C72°F22°C9 mph14 km/h from SouthPartly CloudyMostly Cloudy
September 1256°F13°C70°F21°C10 mph16 km/h from SouthMostly ClearMostly Clear
September 1352°F11°C71°F21°C5 mph8 km/h from WestMostly ClearPartly Cloudy

Yes

Low of 55°F13°C, High of 79°F26°C
Wind: 7 mph11 km/h
Precipitation: None

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