Will I be cold?
Will I be cold in Seoul in January?
Verdict
Yes — Yes, cold.
Lows drop to 21°F on average — noticeably cold, especially after sundown.
Day vs. night
Day
36°F
Cold
Direct sun feels cool at best; shade is jacket weather.
Night
21°F
Freezing
Deep freeze after sunset — every exposed step counts.
Why
Seoul in January averages highs of 36°F, lows of 21°F, 6 rainy days.
Plan for real winter kit — an insulated coat, warm hat, and gloves rather than a light jacket.