Spring (March–May)
Cherry blossoms usually peak in early April in Seoul and a little earlier in Busan. Pleasant days, chilly nights, and some fine-dust days, so pack a mask.
Summer (June–August)
Hot and humid, with the monsoon (jangma) from late June to July. Typhoons can affect Busan from August to September. Good for beaches and Han River nights.
Autumn (September–November)
The best time for most travelers. Leaves peak around late October to mid-November in Seoul and Nami Island. Crisp, dry and very photogenic.
Winter (December–February)
Seoul often drops below zero, sometimes to -10°C, with occasional snow. Busan is milder. Think light festivals, ski day trips and hot street food. Bring a thick coat, gloves and thermals.