Will I be cold?
Will I be cold in Seoul in December?
Verdict
Yes — Yes, cold.
Lows drop to 24°F on average — noticeably cold, especially after sundown.
Day vs. night
Day
38°F
Cold
Direct sun feels cool at best; shade is jacket weather.
Night
24°F
Freezing
Deep freeze after sunset — every exposed step counts.
Why
Seoul in December averages highs of 38°F, lows of 24°F, 5 rainy days.
Plan for real winter kit — an insulated coat, warm hat, and gloves rather than a light jacket.