Overview
- The Japan Meteorological Agency, which on Friday adopted the term “kokusho-bi,” will use it in forecasts when temperatures exceed 40°C.
- JMA says the label is meant to prompt greater vigilance during extreme heat to reduce health risks.
- The name was chosen through an online survey run in February and March that offered 13 options, drew about 478,000 responses, and included expert input.
- The agency cited a surge in extreme heat, noting 108 days above 40°C since 1872 with 41 of them recorded from 2023 to 2025, alongside record heat in summer 2025.
- The new tier joins existing terms that flag rising heat: natsubi above 25°C, manatsubi above 30°C, and moshobi above 35°C.