Seoul's fares move with its four distinct seasons — but not always the way you'd guess. The most beautiful weeks (cherry blossom and autumn foliage) are also the most expensive to fly into, so knowing when demand actually peaks matters as much as knowing when the weather's nicest.
The cheapest months to fly
Winter outside the New Year holidays (mid-January through February) and the summer monsoon stretch (late June through July) tend to be Seoul's softer fare windows. Spring cherry blossom season (first half of April) and peak autumn foliage (October) are the two windows where demand — and prices — climb the most, so shifting a trip a few weeks either side of those can make a real difference.
How far ahead to book
2 to 4 months out is generally the sweet spot for long-haul flights into Seoul. If cherry blossoms or autumn colors are the actual point of the trip, book earlier — 4 to 5 months out — since those short, specific windows sell out and climb in price faster than the rest of the year.
Watch out for these price spikes
- Cherry blossom season, first half of April — Seoul's most in-demand and priciest stretch
- Autumn foliage, October — the second major seasonal spike
- Chuseok (Korean thanksgiving, dates shift yearly with the lunar calendar, usually September or early October) — major domestic travel holiday that tightens flight and hotel availability
- Seollal (Lunar New Year, January or February) and the Christmas–New Year stretch — both push up demand on top of already-cooler pricing elsewhere in winter
A few practical habits that help
Incheon is Seoul's main international gateway for almost all long-haul routes, so airport choice isn't usually a lever here the way it can be in cities with multiple major airports. What does help is a flexible-date search — since Seoul's price swings between seasons are so pronounced, seeing a full month of fares at once makes it much easier to spot the cheaper week rather than guessing.
The short version
Aim for mid-January–February or late June–July if your dates can move, book 2–4 months ahead (earlier for cherry blossoms or fall foliage specifically), and budget extra around Chuseok, Seollal, and the Christmas–New Year window.