Yes

you do need a jacket based on the weather in Roodepoort, South Africa 1 second ago

Why? Because it's cool. Pleasantly cool, but cool!

51°F11°C & Clear

Wind is 3 mph5 km/h from the South, gusting to 9 mph14 km/h

Date	Low	High	Wind	Day	Night
June 15	41°F5°C	64°F18°C	3 mph6 km/h from Southwest	Mostly Clear	Clear
June 16	41°F5°C	67°F19°C	5 mph8 km/h from Southwest	Clear	Clear
June 17	43°F6°C	67°F19°C	7 mph11 km/h from Southwest	Clear	Clear
June 18	44°F7°C	66°F19°C	6 mph9 km/h from Northwest	Clear	Clear
June 19	46°F8°C	67°F20°C	8 mph13 km/h from West	Clear	Clear
June 20	40°F5°C	65°F18°C	4 mph7 km/h from Southeast	Clear	Clear
June 21	41°F5°C	64°F18°C	6 mph10 km/h from Northwest	Clear	Clear

Low of 41°F5°C, High of 67°F20°C
Wind: 5 mph8 km/h
Precipitation: None