Torrential thunderstorms swept western Japan on 25 August, dumping an estimated 110 millimetres of rain in an hour on the Hyogo Prefecture cities of Tamba-Sasayama and neighbouring Tamba. The Japan Meteorological Agency issued its highest-level "record-short-duration heavy rain" alert, warning residents to move to higher ground as the risk of flash flooding and landslides escalated. In nearby Kyoto, the Tenjingawa River surged above its flood-danger mark, and municipal authorities placed the prefectural capital under a flood warning. Additional flood alerts were later extended to parts of Nagano, Sanda and other municipalities as the storm line tracked east, while forecasters cautioned that further convective bursts could strike Hokkaido and central Honshu on Tuesday. The deluges arrive amid an enduring heatwave. Tokyo registered its eighth consecutive "moshobi"—a day with temperatures at or above 35 °C—bringing the capital’s tally to 21 for the season and setting a new August record. Nationwide, 133 meteorological stations breached the 35 °C threshold on Monday, underscoring the severity of the late-season heat. Authorities advised residents to remain alert for rapid weather changes, monitor official advisories and take precautions against both flooding and heat-related illness. Medical specialists also warned that menthol-based cooling products offer little protection and could heighten the risk of heatstroke.