The Japan Meteorological Agency issued heatstroke alerts for 12 prefectures on Sunday as temperatures in Kyushu approached 40 degrees Celsius [1].
This surge in extreme heat poses a critical public health risk, as the number of prefectures under alert is the highest recorded so far in 2026 [1].
The heatwave is driven by the influence of the Pacific High, which has brought abnormal temperatures to the region [1]. In Hita, Oita Prefecture, the maximum temperature is expected to reach 39 degrees Celsius [1]. Similarly, cities such as Kurume in Fukuoka Prefecture and Kumamoto City are forecast to hit 38 degrees Celsius [1].
Early readings on Sunday already indicated a steep climb in temperature. Fukuoka City recorded 36.1 degrees Celsius, while Masuda in Shimane Prefecture measured 35.6 degrees Celsius [1].
"Heatstroke alerts have been issued for 12 prefectures from Kinki to Kyushu, the most in 2026, and the state of extremely high danger of heatstroke will continue," FNN said [1].
Amidst the heat, the Japan Meteorological Agency announced Sunday morning that the rainy season has officially ended in Shikoku [1]. This transition occurred five days earlier than the average year, although it is 15 days later than the date recorded in 2025 [1].
Local authorities are urging residents to take preventative measures against heat-related illnesses as the Pacific High continues to push temperatures upward [1].
“The number of prefectures under alert is the highest recorded so far in 2026.”
The combination of an early end to the rainy season in some regions and record-breaking heat alerts suggests a volatile summer pattern for Japan. With 12 prefectures under alert, the most for the current year, the strain on public health infrastructure to manage heatstroke cases is likely to increase as the Pacific High stabilizes over the archipelago.
