ha-jma-weather

English | 日本語

A Home Assistant custom integration that exposes weather warnings, advisories, and emergency warnings issued by the Japan Meteorological Agency (JMA / 気象庁) for any municipality in Japan.

It polls the official JMA disaster-prevention XML (R06 集約通報, VPWS50) and creates, per location, an aggregate sensor (number of active warnings) plus one binary_sensor per phenomenon (thunderstorm, heavy rain, flood, …).

Status: Phase 2b (warnings/advisories + disaster-prevention info). Weather forecast and precipitation nowcast are on the roadmap below.

• 🗾 Pick any municipality in Japan from a UI dropdown — no manual codes
• ⚡ One binary_sensor per phenomenon (on while issued/continuing) — easy automations
• 📊 Aggregate sensor with the full active-warning list in attributes
• 🚨 Emergency Warning (特別警報) detection
• 📍 Multiple locations (add the integration once per location)
• 🔁 Robust against JMA's "no warning" placeholder quirk; auto-recovers from fetch failures
• 🌐 Minimal dependencies — Home Assistant's built-in HTTP client + defusedxml (safe XML parsing)

1. HACS → Integrations → ⋮ (top-right) → Custom repositories
2. Add https://github.com/yhi264/ha-jma-weather with category Integration
3. Install JMA Weather, then restart Home Assistant

Once this repository is published to the HACS default store, the custom-repository step will no longer be necessary.

Copy custom_components/jma_weather/ into your Home Assistant config/custom_components/ directory and restart.

Settings → Devices & Services → Add Integration → JMA Weather. The setup wizard fetches area.json and walks you through:

1. Forecast region (prefecture / 府県予報区) — dropdown
2. Municipality (市町村) — dropdown
3. Coordinates — defaults to your Home Assistant home location; editable (saved for the Phase 2d precipitation nowcast)

Options (changeable later): update interval in seconds (default 300 = 5 min, minimum 60). Note: the warning data source is a single nationwide document shared by one coordinator across all locations, so the warning poll interval is taken from the first-configured location; the per-location disaster-info poll honors each location's interval.

• sensor.jma_weather_<class20>_warnings — number of active warnings/advisories (int)
  • Attributes: summary (e.g. 雷注意報・大雨警報 / なし), warnings (list of {code, name, level, status} — level is the warning's 警戒レベル or null), max_level (highest active 警戒レベル, or null if none), has_special_warning, report_datetime, area_name
  • Example: sensor.jma_weather_4044700_warnings

• binary_sensor.jma_weather_<class20>_<group> — on while that phenomenon is issued (発表) or continuing (継続) (device_class: safety)
  • Attributes: level (the warning's 警戒レベル, or null), status. A single phenomenon spans advisory→warning→emergency levels; level reflects the highest active one.
  • Example: binary_sensor.jma_weather_4044700_kaminari

Note: In the R06 format, flood (洪水) warnings are distributed via the 指定河川洪水予報 (VXKO) product, not this warning feed; the kozui sensor currently has no data source and remains off (planned for a future release).

Attributes: info_type, report_datetime, headline, plus valid_until (tornado) and target_areas (landslide).

Add the integration once per location (1 config entry = 1 location). Locations in the same prefecture register as independent entries; entities and devices never collide (keyed by municipality code).

automation:
  - alias: Notify on thunderstorm advisory
    trigger:
      - platform: state
        entity_id: binary_sensor.jma_weather_4044700_kaminari
        to: "on"
    action:
      - service: notify.mobile_app
        data:
          message: "A thunderstorm advisory has been issued for your area."

Data: Japan Meteorological Agency disaster-prevention information (https://www.jma.go.jp/bosai/). This project is not affiliated with or endorsed by the JMA.

• Phase 2c: Weather forecast, temperature, precipitation probability → Home Assistant weather entity
• Phase 2d: Precipitation nowcast — "rain starts/stops in N minutes" (tile sampling)

python3 -m venv .venv
./.venv/bin/pip install -r requirements-test.txt
./.venv/bin/pytest tests/ -q

MIT License © 2026 yhi264