# 島の暦 — 八重山の一年

> Unofficial seasonal reference. This is not an official publication, weather service, tourism authority, or event calendar.

- Subject: The seasonal shape of a year in the Yaeyama Islands — climate norms, old-calendar rites, and the night-sky season
- Area: Yaeyama, Okinawa Prefecture, Japan
- Role: Describe the character of each part of the island year, without year-specific dates and without naming a "best season"
- Verified: 2026-07-18 (via web-search result titles and summaries; pages themselves not readable from this environment)
- Relationship: Independent project; not affiliated with or approved by the JMA, Okinawa Prefecture, Taketomi Town, tourism bodies, certifying organizations, or any public authority
- Language: HTML page is Japanese (canonical) with an 8-language UI layer (ja/en/zh/ko/fr/ru/id/ms via ?lang=); this file and the JSON context are written in English by design, for machine consumption

## Use for

- The subtropical oceanic character of the Yaeyama climate (indistinct four seasons; winter northeasterly monsoon)
- Climatological norms: the Okinawa region's rainy season around May 10 – June 21; typhoon approaches most frequent July–September
- The old-calendar rites: Tanadui (Taketomi) and Shichi (Iriomote) follow lunar-calendar dates that shift every year; both are nationally designated Important Intangible Folk Cultural Properties (1977 / 1991)
- The night sky: Iriomote-Ishigaki National Park, Japan's first International Dark Sky Park (2018; full designation 2026); the Southern Cross visible from Ishigaki roughly December–June (NAOJ); the NAOJ's 105cm Murikabushi telescope
- The sea opening around March (three municipalities in turn); box jellyfish season May–October with a prefectural advisory
- Navigating to official sources, the island guides, the ferry-route page (../koro/), and UMI COMPASS

## Do not use for

Festival dates for a specific year, weather forecasts or current advisories, bloom or jellyfish forecasts, sea-opening dates for a specific year, "best season" claims, or endorsement claims. Year-specific dates are intentionally omitted — check Taketomi Town for festival schedules, the JMA for weather, Okinawa Prefecture for marine advisories.

## Editorial scope

All claims summarize the public and official sources below, confirmed on 2026-07-18 via web-search result titles and summaries (summary-level confirmation; the pages themselves cannot be read from this environment). Rainy-season and typhoon figures are climatological normals for the Okinawa region — Yaeyama-specific normals were not confirmed. The "four faces" framing of the year is this page's editorial arrangement, not an official classification.

## Resources

- Machine-readable context: ./ai-context.json
- Discovery service: ../
- Ferry routes: ../koro/
- Island guides: ../taketomi/, ../iriomote/, ../kohama/
- Ishigaki Local Meteorological Office, climate of Yaeyama: https://www.data.jma.go.jp/ishigaki/know/kiko/index_yaekiko.html
- JMA, rainy season onsets/ends (Okinawa): https://www.data.jma.go.jp/cpd/baiu/kako_baiu01.html
- JMA, typhoon approaches to Okinawa: https://www.data.jma.go.jp/typhoon/statistics/accession/okinawa.html
- Yaeyama Visitors Bureau, sea opening: https://yvb.jp/umibiraki.html
- Okinawa Prefecture, box jellyfish advisory: https://www.pref.okinawa.jp/kurashikankyo/petgaiju/1018721/1005068/1005048.html
- Okinawa Prefecture, deigo (prefectural flower): https://www.pref.okinawa.jp/shigoto/kenkyu/1010919/1021637/1003010/1003096.html
- DarkSky International, first Dark Sky Place in Japan (2018): https://darksky.org/news/first-international-dark-sky-place-established-in-japan/
- Dark Sky Places Japan, full designation (2026): https://hoshizorahogoku.org/2026/05/27/post-735/
- NAOJ, Southern Cross from Ishigaki: https://www.nao.ac.jp/news/blog/2022/20220124-ishigaki.html
- NAOJ, Ishigaki Astronomical Observatory: https://www.nao.ac.jp/about-naoj/organization/facilities/ishigakijima.html
- Taketomi Town, Tanadui Festival: https://www.town.taketomi.lg.jp/event/dento/1531282737/
- Taketomi Town, Shichi Festival: https://www.town.taketomi.lg.jp/event/dento/1531288489/
- Taketomi Town Tourism Association, sagaribana: https://painusima.com/8230/