Overview
- The Japan Meteorological Agency introduced 'kokushobi' for forecast days above 40°C after a public survey and expert review.
- Meteorological records show a sharp shift, with 41 of 108 days over 40°C since 1872 occurring between 2023 and 2025.
- The summer of 2025 was the hottest on record, averaging 2.36°C above the 30‑year norm as 132 of 153 stations set new highs.
- Japan’s national record now stands at 41.8°C in Isesaki, Gunma, recorded in August 2025 when 30 locations across 13 prefectures topped 40°C.
- Health services face growing strain as heatstroke cases jump above 35°C, and experts forecast another record summer in 2026.