The Japan Meteorological Agency announced Monday morning that the rainy season has ended for the southern region of Kyushu [1].
This transition marks the onset of a severe heatwave across western Japan, creating a significant public health risk as temperatures climb rapidly. The shift is driven by a Pacific high-pressure system that has moved into the region following the seasonal rains [2].
Heat-stroke alerts are currently in effect for 14 prefectures, spanning from Kinki to Kyushu [1]. This represents the highest number of concurrent alerts issued so far in 2026 [1]. The agency said the peak of this heat is expected to last through Wednesday, July 17 [1, 2].
The end of the rainy season on July 13 occurred two days earlier than the historical average [2]. However, it arrived 16 days later than it did in 2025 [2].
Extreme temperatures have already been recorded across several cities. In Iwakuni, Yamaguchi, the temperature reached 35.9 °C by 11 a.m. [2]. Forecasts indicate even higher peaks, with Yamaguchi city expected to reach 37 °C [2].
Other regions are facing similar extremes. Forecasts for Hita in Oita and the city of Toyama both predict maximum temperatures of 38 °C [1, 2]. These figures underscore the intensity of the current weather pattern affecting the western part of the archipelago.
Local authorities continue to monitor the situation as the region adjusts to the sudden shift from rain to intense heat. The agency said the widespread alerts are necessary to prevent heat-related illnesses during this peak period [1].
“Heat-stroke alerts are currently in effect for 14 prefectures, spanning from Kinki to Kyushu.”
The rapid transition from the rainy season to a high-pressure system often creates a 'shock' period where humidity remains high while temperatures spike, increasing the risk of heatstroke. The fact that 14 prefectures are under alert—a 2026 record—suggests a more synchronized and intense heat event than seen earlier in the year, potentially straining local healthcare systems and energy grids during the mid-July peak.
