Yes

you do need a jacket based on the weather in Ljubljana, Slovenia 1 second ago

Why? Because it's pretty chilly.
51°F11°C & Mostly Clear

Wind is 6 mph10 km/h from the W, gusting to 14 mph22 km/h
March 28
7pm51°F10°C6 mph10 km/h WMostly Clear
8pm49°F9°C5 mph7 km/h SWMostly Clear
9pm48°F9°C3 mph5 km/h WMostly Clear
10pm47°F8°C3 mph5 km/h SWPartly Cloudy
11pm46°F8°C3 mph4 km/h SWMostly Clear
March 29
12am46°F8°C2 mph4 km/h SWPartly Cloudy
1am46°F8°C2 mph4 km/h SWMostly Cloudy
2am49°F9°C3 mph4 km/h SWMostly Cloudy
3am51°F11°C4 mph6 km/h SWMostly Cloudy
4am54°F12°C6 mph10 km/h SWMostly Cloudy
5am57°F14°C8 mph12 km/h SWMostly Cloudy
6am60°F15°C9 mph15 km/h SWMostly Cloudy
DateLowHighWindDayNight
March 2744°F7°C55°F13°C8 mph13 km/h from SWRainPartly Cloudy
March 2846°F8°C64°F18°C8 mph12 km/h from SWMostly CloudyMostly Clear
March 2945°F7°C70°F21°C4 mph7 km/h from SWPartly CloudyRain
March 3048°F9°C64°F18°C8 mph13 km/h from SWMostly CloudyMostly Cloudy
March 3149°F9°C63°F17°C7 mph11 km/h from SWRainDrizzle
April 145°F7°C61°F16°C5 mph8 km/h from SWRainMostly Clear
April 241°F5°C61°F16°C7 mph11 km/h from SWMostly CloudyDrizzle

Yes

Low of 46°F8°C, High of 64°F18°C
Wind: 8 mph12 km/h
Precipitation: None

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