Overview
- The Japan Meteorological Agency will put the new five-level alerts into use on May 28 and will apply the same numbered scale to river flooding, heavy rain, landslides and storm surge.
- A new Level 4 labeled a 'danger warning' is meant to prompt pre-disaster evacuation while Level 5 denotes disaster already occurring, so authorities urge residents to treat Levels 3 and 4 as the critical window for action.
- The formal term 'flood' (洪水) will be removed from official disaster-weather wording as part of the change to make names match action more directly.
- Government back-testing using May–November 2025 rainfall data shows Level 4 heavy-rain warnings would have risen sharply in some places—for example, Fukuoka would have recorded about 40 Level 4 issuances—raising concerns about more frequent evacuation advisories and local capacity to open shelters.
- Broadcasters, municipal disaster leaders and app providers are scrambling to update scripts, procedures and smartphone alerts (Yahoo! 防災速報 has over 70 million downloads) because public understanding, notification settings and clear on-air phrasing are essential for the system to trigger timely evacuations.