Yes

you do need a jacket based on the weather in St Kilda VIC 3182, Australia 1 second ago

Why? Because it's cold. simple as that.
45°F7°C & Mostly Cloudy

Wind is 2 mph3 km/h from the NE, gusting to 6 mph9 km/h
May 3
6pm45°F7°C2 mph4 km/h NEMostly Cloudy
7pm47°F8°C2 mph4 km/h NEMostly Cloudy
8pm50°F10°C2 mph3 km/h NEMostly Cloudy
9pm53°F12°C1 mph2 km/h NEMostly Cloudy
10pm56°F13°C2 mph3 km/h SMostly Cloudy
11pm57°F14°C2 mph4 km/h SPartly Cloudy
May 4
12am59°F15°C2 mph3 km/h SWMostly Cloudy
1am60°F15°C2 mph4 km/h SWMostly Cloudy
2am60°F16°C3 mph5 km/h SWMostly Cloudy
3am59°F15°C4 mph6 km/h SWMostly Cloudy
4am57°F14°C4 mph6 km/h SWMostly Cloudy
5am57°F14°C3 mph5 km/h SWMostly Cloudy
DateLowHighWindDayNight
May 344°F7°C60°F16°C3 mph4 km/h from SWMostly CloudyPartly Cloudy
May 448°F9°C66°F19°C7 mph11 km/h from SEPartly CloudyClear
May 551°F11°C66°F19°C8 mph13 km/h from SEMostly ClearClear
May 647°F8°C65°F18°C4 mph6 km/h from EClearMostly Clear
May 748°F9°C61°F16°C4 mph6 km/h from SEPartly CloudyPartly Cloudy
May 849°F10°C60°F16°C4 mph7 km/h from SPartly CloudyPartly Cloudy
May 951°F11°C66°F19°C5 mph8 km/h from SPartly CloudyMostly Clear

Yes

Low of 48°F9°C, High of 66°F19°C
Wind: 7 mph11 km/h
Precipitation: None

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