No

Why? Because you should be inside at home! #StayHome

But if you absolutely had to go out to get groceries, medication or other essential travel, No, you don't need a jacket.

Based on the weather in Seoul, South Korea as of May 27, 2020 12:05pm local time.

Now

Clear
Temp: 74°F24°C
Wind: 6 MPH10 KPH
Precipitation: None

Today

Next 2 hours: No

Next 4 hours: No

Next 8 hours: No

Tomorrow

Yes

Clear throughout the day.
Low of 55°F13°C, High of 74°F24°C
Wind: 5 MPH8 KPH
Precipitation: 5% rain