Mt. Fuji Weather Station Day

What Is Mt. Fuji Weather Station Day?

Every August 30th is "Mt. Fuji Weather Station Day" (富士山測候所記念日, Fujisan Sokkojo Kinenbi) in Japan. On August 30, 1895, Nonaka Itaru (野中到, also written 至) completed an observation hut he had built at his own expense on Kengamine, the summit of Mt. Fuji. His observatory is regarded as the forerunner of the Japan Meteorological Agency's Mt. Fuji Weather Station. It is a day to look back on the pioneers who took on weather observation in harsh conditions.

The Challenge of Nonaka Itaru and Chiyoko

Weather observation at the summit of Mt. Fuji began not as a government project, but with one private citizen's passion.

• An observation hut built with his own money: Nonaka, a member of the Meteorological Society of Japan, aimed to observe the weather at the summit year-round. After climbing Mt. Fuji in winter in early 1895, he built a wooden hut of about 20 square meters on Kengamine that summer.
• A couple observing in the depths of winter: He began observing at the summit in October, and his wife Chiyoko joined him in mid-October. But both fell ill from altitude sickness and malnutrition, and in late December they were rescued and brought down the mountain by engineers from the Central Meteorological Observatory.
• The novel "Fuyo no Hito": The couple's challenge became widely known and was later portrayed in Nitta Jiro's novel "Fuyo no Hito."

The National Weather Station and the Mt. Fuji Radar

Nonaka's ambition was later carried on by the government.

• A national observatory opens: In 1932, the Central Meteorological Observatory set up a temporary observatory at the summit, and in 1936 it moved to Kengamine and became permanent.
• The Mt. Fuji Radar: After the severe damage caused by the Isewan Typhoon in 1959, a weather radar was installed at the summit in 1964. It could detect rain clouds within a radius of about 700 km and played a major role in tracking typhoons, but it was retired in 1999 as weather satellites and other technology advanced.

Fun Facts About the Mt. Fuji Weather Station

• Unstaffed since 2004: Staff stopped living at the station on October 1, 2004. Today, as the "Mt. Fuji Special Regional Weather Station," automatic equipment continues to observe temperature, air pressure and more.
• A summer research base: In summer, the facility is rented by a nonprofit group that uses it for various research, such as measuring carbon dioxide and air pollutants in the atmosphere.
• The radar dome moved to Yamanashi: The radar dome, once a symbol of the summit, was dismantled and moved to the "Mt. Fuji Radar Dome Museum" in Fujiyoshida, Yamanashi Prefecture, where visitors can see it.
• Lukewarm boiling water: Because air pressure is low at the summit, water boils at a temperature well below 100°C.

Tips for Marking This Day

• Check the Japan Meteorological Agency's rain radar and think about the observation history behind today's forecasts
• Read Nitta Jiro's "Fuyo no Hito" to learn about the Nonakas' challenge
• Get ready for typhoon season by checking your emergency supplies and evacuation sites
• Plan a visit to related places such as the Mt. Fuji Radar Dome Museum

One Person's Challenge Became a Foundation for Weather Forecasting

August 30th is the day a private citizen in the Meiji era completed an observation hut at the summit of Mt. Fuji. His challenge ended without the results he had hoped for, but his ambition was carried on by the national weather station and the Mt. Fuji Radar. Today, why not take a moment to think about the long history of observation behind the weather forecasts we see every day?