Yes

you do need a jacket based on the weather in Westmead NSW 2145, Australia 1 second ago

Why? Because it's not very warm out!

52°F11°C & Mostly Cloudy

Wind is 2 mph4 km/h from the Northwest, gusting to 6 mph10 km/h

Date	Low	High	Wind	Day	Night
June 1	49°F10°C	66°F19°C	2 mph3 km/h from Northwest	Cloudy	Mostly Cloudy
June 2	51°F10°C	68°F20°C	5 mph8 km/h from South	Mostly Clear	Drizzle
June 3	46°F8°C	59°F15°C	9 mph15 km/h from Southwest	Drizzle	Clear
June 4	41°F5°C	63°F17°C	4 mph6 km/h from Southwest	Clear	Partly Cloudy
June 5	41°F5°C	61°F16°C	2 mph4 km/h from Northwest	Mostly Cloudy	Mostly Cloudy
June 6	46°F8°C	65°F19°C	4 mph7 km/h from Northwest	Partly Cloudy	Clear
June 7	44°F7°C	63°F17°C	8 mph12 km/h from Northwest	Mostly Clear	Mostly Clear

Low of 51°F11°C, High of 68°F20°C
Wind: 5 mph8 km/h
Precipitation: None