Yes

you do need a jacket based on the weather in Pyeongtaek-si, Gyeonggi-do, South Korea 1 second ago

Why? Because it's quite chilly.
50°F10°C & Clear

Wind is 2 mph3 km/h from the S, gusting to 4 mph6 km/h
May 2
6pm52°F11°C2 mph3 km/h SClear
7pm57°F14°C1 mph2 km/h SWClear
8pm62°F17°C2 mph3 km/h WClear
9pm67°F19°C3 mph4 km/h WClear
10pm72°F22°C4 mph7 km/h WClear
11pm75°F24°C5 mph9 km/h NWClear
May 3
12am77°F25°C6 mph10 km/h WClear
1am79°F26°C6 mph10 km/h WClear
2am79°F26°C7 mph11 km/h WClear
3am78°F26°C8 mph12 km/h WClear
4am76°F25°C9 mph14 km/h WClear
5am73°F23°C8 mph13 km/h WClear
DateLowHighWindDayNight
May 248°F9°C79°F26°C5 mph8 km/h from WClearClear
May 349°F10°C83°F28°C5 mph8 km/h from WMostly CloudyRain
May 461°F16°C66°F19°C10 mph17 km/h from SEThunderstormsThunderstorms
May 556°F13°C65°F18°C10 mph16 km/h from SWRainDrizzle
May 654°F12°C64°F18°C6 mph10 km/h from EDrizzleCloudy
May 750°F10°C67°F19°C7 mph11 km/h from NEPartly CloudyClear
May 846°F8°C71°F21°C6 mph10 km/h from WClearClear

Yes

Low of 49°F10°C, High of 82°F28°C
Wind: 5 mph8 km/h
Precipitation: None

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