The Japan Meteorological Agency forecast temperatures reaching 40 °C in the Tokai region starting Tuesday, July 21 [1].
This extreme heat event triggers urgent public health warnings as officials attempt to prevent widespread heat-stroke casualties during a period of intense summer sun. The severity of the forecast has prompted authorities to issue heat-stroke alerts across 42 prefectures [1].
Forecasters identified Toyoda City in Aichi Prefecture and Tajimi City in Gifu Prefecture as the primary areas expected to hit the 40 °C mark [1]. These conditions are the result of strong summer sun following the end of the rainy season [1, 2]. The extreme heat is expected to persist through the weekend, lasting until approximately July 26 [1].
High temperatures are also projected for the Kanto region. Isesaki in Gunma Prefecture and Kumagaya in Saitama Prefecture are predicted to reach 38 °C [1]. Meanwhile, central Tokyo is forecast to hit 36 °C [1].
This spike is part of a broader climatic trend. The Japan Weather Association previously noted that between six and 10 locations nationwide were expected to experience such extreme-heat days during 2026 [2]. The association said, "全国で延べ6～10地点が酷暑日になる見込みです" [2].
Local authorities are urging residents to stay hydrated and use air conditioning to mitigate the risks associated with these temperatures. The combination of high heat and humidity in these specific urban and industrial hubs increases the risk of heat-related illnesses for outdoor workers, and the elderly [1, 3].
“Temperatures reaching 40 °C in the Tokai region”
The increasing frequency of 40 °C days in Japan reflects a shift in summer weather patterns where post-rainy-season heat is becoming more intense. By issuing alerts across 42 prefectures, the government is acknowledging that extreme heat is no longer a localized phenomenon but a systemic public health risk affecting the majority of the country's administrative regions.
