Alishan in high summer is a lesson in humidity and tour-bus lots. Alishan in late September is a different mountain: the first hints of the leaf change are still weeks away, but the mist sits in the tea rows in the morning, and the forest railway feels like a railway again rather than a ride.

If you are going, book the Chiayi HSR connection and the mountain transport together. Same-day improvisation is how you spend an afternoon in a 7-Eleven parking lot. Stay a night if you can; the sunrise economy is real, and it is also the only way to see the terraces before the day-trip arrives.

This is not a secret. It is simply a calendar. The people who live here and still go up the mountain are the ones who pick a Thursday in shoulder season. You can do the same.