Japan issued heatstroke alerts for 25 prefectures on Wednesday, including the Tohoku and Kanto regions for the first time this year [5].
The alerts follow a period of persistent extreme heat where temperatures are approaching or exceeding human body temperature. This trend creates a high risk of heatstroke for residents and visitors across the affected areas.
Forecasters predicted maximum temperatures of 38 °C in Kofu, Yamanashi, and Nagaoka, Niigata [1]. High temperatures were also forecast for Maebashi, Gunma, and Nagoya, Aichi.
Recent data shows the heatwave is already impacting several cities. On July 14, Hamamatsu, Shizuoka, recorded an observed temperature of 38.3 °C [2]. In Fuchu, Tokyo, the observed high reached 36.9 °C [3].
These spikes are part of a broader pattern of extreme weather this season. A total of 170 locations have recorded a ‘猛暑日’ — or extremely hot day — so far in 2026 [4].
The expansion of these alerts into the Tohoku and Kanto regions marks a significant escalation in the summer's weather patterns. Authorities are monitoring the situation as temperatures continue to climb in several urban centers.
“Japan issued heatstroke alerts for 25 prefectures”
The issuance of alerts in the Tohoku and Kanto regions for the first time this year indicates a widening geographic footprint of extreme heat across Japan. With 170 locations already recording extremely hot days, the scale of this heatwave suggests a heightened pressure on public health infrastructure and energy grids to maintain cooling services.
