Yes

you do need a jacket based on the weather in Adelaide SA, Australia 1 second ago

Why? Because it's not very warm out.
56°F13°C & Mostly Clear

Wind is 8 mph13 km/h from the S, gusting to 16 mph26 km/h
April 18
6pm56°F14°C8 mph13 km/h SMostly Clear
7pm59°F15°C8 mph14 km/h SMostly Clear
8pm61°F16°C10 mph16 km/h SPartly Cloudy
9pm63°F17°C10 mph16 km/h SPartly Cloudy
10pm65°F18°C10 mph16 km/h SEPartly Cloudy
11pm66°F19°C11 mph17 km/h SPartly Cloudy
April 19
12am67°F19°C11 mph18 km/h SPartly Cloudy
1am66°F19°C12 mph19 km/h SPartly Cloudy
2am66°F19°C12 mph19 km/h SMostly Clear
3am64°F18°C11 mph18 km/h SMostly Clear
4am62°F17°C10 mph17 km/h SMostly Clear
5am60°F16°C9 mph14 km/h SMostly Clear
DateLowHighWindDayNight
April 1855°F13°C67°F19°C10 mph17 km/h from SPartly CloudyMostly Clear
April 1952°F11°C71°F21°C6 mph9 km/h from SEClearMostly Clear
April 2049°F9°C71°F22°C3 mph6 km/h from SWClearClear
April 2152°F11°C75°F24°C5 mph8 km/h from NWClearPartly Cloudy
April 2256°F13°C70°F21°C10 mph15 km/h from SWMostly CloudyMostly Cloudy
April 2353°F12°C64°F18°C9 mph14 km/h from SWPartly CloudyPartly Cloudy
April 2452°F11°C66°F19°C9 mph15 km/h from SWMostly CloudyPartly Cloudy

Yes

Low of 52°F11°C, High of 71°F22°C
Wind: 6 mph9 km/h
Precipitation: None

Support This Page