The Japan Meteorological Agency declared the rainy season over for the Kanto-Koshin and Tokai regions on Monday [1].
The transition signals the start of a severe heat wave that could pose significant public health risks across the country. A strong high-pressure system is currently pushing hot air across the archipelago, prompting officials to issue heat-stroke alerts for most regions from Tohoku to Kyushu [1, 2].
This year's rainy season ended one day later than the average date [1]. Compared to the previous year, the end of the rainy season arrived 23 days later [1].
Forecasters expect extreme temperatures today. The highest forecast temperature is 38°C in Kofu and Kumagaya, located in Saitama Prefecture [1]. Tokyo is expected to reach 36°C [1], while Sapporo is forecast at 27°C [1].
The heat is expected to intensify further this week. The agency forecast temperatures reaching 40°C in Nagoya and Gifu on Wednesday and Thursday [1].
Local authorities are urging residents to take precautions against heat-stroke as the high-pressure system maintains its grip on the region [2].
“The rainy season ended one day later than the average date.”
The delayed end of the rainy season combined with an immediate shift to extreme heat creates a volatile transition for Japan's infrastructure and public health systems. The forecast of 40°C temperatures in central cities indicates a severe heat wave that may increase energy demands for cooling and elevate the risk of heat-related hospitalizations.
