
Autumn is Nikko's moment — but timing splits by altitude. The mountains (Irohazaka, Lake Chuzenji) peak in mid-to-late October, the shrine town a couple of weeks later in early November. Either is spectacular and very busy, so go on a weekday and start early. Outside autumn, summer is a cool mountain escape and winter brings atmospheric snow on the shrines.
On peak-autumn days the Irohazaka mountain road jams for hours — go up early and come down before mid-afternoon, and reserve your return train. If you only care about the shrines, the town's colour in early November is easier to time than the mountains.
Autumn — the mountains peak in mid-to-late October and the shrine town in early November. Both are stunning and crowded, so go on a weekday and start early.
It moves down the mountain: Lake Chuzenji and Irohazaka in mid-to-late October, then the Toshogu shrine area in early November.