Japan's weather agency warns of rare once-in-a-decade heat around September 9 across nine regions

Japan's Meteorological Agency issued an early warning on September 3 for unusually high temperatures, expected around September 9, with a likelihood of once-in-a-decade heat across nine regions including Tohoku, Kanto-Koshin, Hokuriku, Tokai, Kinki, Chugoku, Shikoku, and northern/southern Kyushu. The warning, based on a 30% probability of five-day average temperatures exceeding thresholds like +2.6°C in Tohoku and +2.5°C in Kanto-Koshin, follows cooler conditions from a front and moist air, with warm air inflows expected to drive the spike. Authorities advise caution for crop and livestock management and heatstroke prevention. Early weather information is issued when extreme temperatures or snowfall are likely, typically on Mondays and Thursdays, covering six to fourteen days ahead. The agency also notes that heat advisories and alerts will be issued for shorter-term risks.