What Is Koyo?
Koyo (紅葉) — sometimes written momiji — refers to the Japanese custom of appreciating the changing colours of autumn leaves. Just as hanami celebrates cherry blossoms in spring, koyo is a beloved seasonal ritual in which people visit parks, mountain valleys, and temple gardens to witness the transformation of the landscape into vivid shades of red, orange, and gold.
The word itself is written with characters meaning "crimson leaves," and the season typically runs from late September through December, moving progressively southward and from higher elevations to lower ones.
The Science of Autumn Colour
As days shorten and temperatures cool, deciduous trees stop producing chlorophyll — the green pigment that dominates leaves in summer. As chlorophyll breaks down, other pigments are revealed or newly produced:
- Carotenoids (yellows and oranges) were always present but masked by green chlorophyll.
- Anthocyanins (reds and purples) are actively produced in autumn, especially during sunny days following cold nights.
This is why clear, sunny days combined with cool nights produce the most vivid koyo displays. Warm, cloudy autumns result in duller colours.
The Best Trees for Koyo
| Tree | Japanese Name | Colour |
|---|---|---|
| Japanese Maple | Momiji (もみじ) | Crimson, scarlet, orange |
| Ginkgo | Ichō (いちょう) | Pure golden yellow |
| Japanese Zelkova | Keyaki (けやき) | Amber, rust-red |
| Japanese Beech | Buna (ぶな) | Golden yellow to brown |
| Katsura | Katsura (かつら) | Yellow; smells of caramel |
| Sumac | Urushi / Hazenoki | Intense scarlet |
When Does Koyo Happen?
The koyo front (koyo zensen) travels from north to south and from mountain to valley across Japan:
- Late September – October: Hokkaido, high mountain areas (e.g., the Japanese Alps, Nikko highlands)
- Late October – mid-November: Tohoku, Nikko, Nikkō, mountain areas of central Honshu
- Mid-November: Tokyo, Kyoto, Osaka, Kamakura
- Late November – December: Western Japan, Hiroshima, Kyushu
Japan's major weather services publish annual koyo forecast maps, making it easier to plan visits at peak colour.
Iconic Koyo Destinations
- Nikko, Tochigi: UNESCO-listed shrines surrounded by ancient cryptomeria and maple-covered mountains. Stunning in late October.
- Arashiyama, Kyoto: The bamboo groves and riverside maples create a painterly scene in mid-November.
- Korankei, Aichi: A valley filled with over 4,000 maple trees — one of Japan's most celebrated koyo spots.
- Towada-Hachimantai National Park: Remote, vast, and utterly wild autumn colour in Tohoku.
- Rikugien Garden, Tokyo: A classic Edo-period garden that hosts popular evening illuminations during peak koyo.
Appreciating Koyo Like a Local
The Japanese approach to koyo is unhurried and sensory. Take time to:
- Look upward through the canopy with light behind the leaves (momijigari — "maple hunting")
- Notice fallen leaves (ochiba) carpeting paths and reflecting in water
- Enjoy seasonal foods: sweet potato, chestnuts, and mushroom dishes that accompany the season
- Visit early morning for soft light and fewer crowds
Koyo is a reminder that transience and beauty are inseparable — and that the most extraordinary natural spectacles are free to all who take the time to look.