Yes

you do need a jacket based on the weather in South Morang VIC 3752, Australia 1 second ago

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

53°F12°C & Cloudy

Wind is 6 mph9 km/h from the Northwest, gusting to 12 mph20 km/h

Date	Low	High	Wind	Day	Night
July 13	42°F5°C	55°F13°C	5 mph8 km/h from Northwest	Partly Cloudy	Drizzle
July 14	45°F7°C	55°F13°C	6 mph10 km/h from Northwest	Drizzle	Partly Cloudy
July 15	44°F7°C	57°F14°C	7 mph12 km/h from Northwest	Drizzle	Mostly Cloudy
July 16	43°F6°C	54°F12°C	9 mph14 km/h from Northwest	Drizzle	Partly Cloudy
July 17	39°F4°C	56°F13°C	4 mph6 km/h from North	Mostly Clear	Partly Cloudy
July 18	43°F6°C	54°F12°C	16 mph26 km/h from North	Windy	Drizzle
July 19	40°F4°C	54°F12°C	8 mph13 km/h from Northwest	Drizzle	Mostly Clear

Low of 45°F7°C, High of 55°F13°C
Wind: 6 mph10 km/h
Precipitation: 34% rain