Zao Onsen and Frost-Covered Trees — Ice Monsters from the Yamagata Side

The Yamagata side of Mt. Zao presents one of Japan's most dramatic winter experiences: a mountain resort village with 1,900-year-old hot springs at its base and the world-renowned juhyo (frost-covered trees), colloquially called "snow monsters," on its upper ridges. Unlike viewing juhyo from the Miyagi side, the Yamagata approach puts you in the hot spring village itself, making possible the incomparable combination of skiing through ice-tree forests by day and soaking in steaming open-air hot springs by night.

Highlights

The juhyo form when freezing clouds from the Sea of Japan envelop the mountain's upper slopes, depositing rime ice on the fir trees (Abies mariesii) in successive layers during nights of -15°C or colder. By January and February, individual trees may be unrecognizable beneath their ice carapaces — 2-meter tall conifers expanding into 4-meter wide white forms. The gondola ride through the ice-tree forest is an experience available nowhere else in Japan at this scale.

Zao Onsen's outdoor baths (rotenburo) at the village center are legendary: highly acidic (pH 1.1) milky white sulfurous water in open-air stone pools, steam rising against snow-covered slopes. The Dai-rotenburo accommodates hundreds of bathers in a communal outdoor setting that feels both ancient and extraordinary.

Ski terrain ranges from gentle nursery slopes to challenging mogul runs, with the juhyo zone traversable on designated pistes in late January and February when formations are at full size.

Getting There & Tips

Bus from Yamagata Station to Zao Onsen (40 minutes). In winter, extra ski-season buses operate. Check juhyo condition reports before booking — formation quality depends on cold snaps and is not guaranteed.

Best Time to Visit

Late January to mid-February for optimal juhyo. The resort season runs December to late March. Combine at least two nights to experience both evening illumination and morning skiing.