Western Japan recorded its highest average temperatures since records began in 1946 during the middle and late portions of July [3].
The unprecedented heat poses a severe public health risk, prompting the Japan Meteorological Agency (JMA) to issue urgent warnings regarding heatstroke prevention as dangerous conditions are expected to persist throughout August.
According to the JMA, the average temperature in western Japan was 2.9°C [1] higher than normal during the middle of July and 2.5°C [2] higher during the late part of the month. These figures mark the highest averages recorded for these periods since the start of statistical tracking in 1946 [3].
Data indicates that as of July 2, 27 locations had already observed extreme heat days with temperatures exceeding 40°C [4]. While this is just below the previous record of 30 locations set in 2026 [5], the overall average temperature increase remains historic.
Meteorologists attribute the spike to a combination of high pressure strengthening near western Japan and the westerly jet stream flowing further north than average. The World Weather Attribution center said that such extreme heat would not have been possible without the influence of global warming.
Forecasts suggest that these high temperatures will continue for approximately one month [6]. In response to the prolonged heatwave, the JMA said, "The Meteorological Agency calls for preparations against heatstroke."
Local authorities in regions including Kumamoto Prefecture have been particularly focused on monitoring vulnerable populations as the heat persists. The JMA continues to monitor the high-pressure systems that are trapping heat across the western region of the archipelago.
“The average temperature in western Japan was 2.9°C higher than normal during the middle of July.”
The convergence of localized high-pressure systems and systemic global warming is pushing Japan's climate toward a new baseline of extreme summer heat. By breaking records that date back to 1946, this event suggests that traditional heat-mitigation infrastructure may no longer be sufficient to protect public health during August peaks.
