Japan is experiencing divergent weather patterns this Wednesday, with intense heat returning to the Kanto region and thunderstorms forecast for the north [1].
These conditions present simultaneous public health and safety risks, ranging from heat-stroke emergencies in central urban hubs to flash flooding risks in northern rural areas.
The Japan Meteorological Agency said that rain and thunderstorms are expected in the Hokuriku region and northern Japan, including Hokkaido and Tohoku [1]. The agency said that some areas may experience heavy rain and lightning strikes [2]. These conditions are being driven by a low-pressure system approaching from the west, which is bringing moist winds into the northern latitudes [2].
Meanwhile, the Kanto region is seeing a sharp return of extreme temperatures. The Japan Meteorological Agency said temperatures in Kanto will rise between five and eight degrees Celsius [2] compared to Tuesday, when many areas remained below 30 degrees Celsius [2]. This shift is caused by high-pressure conditions over central Japan that are trapping hot air across the region [2].
Maximum temperatures across west and east Japan are expected to reach approximately 35 degrees Celsius [2]. Due to these conditions, heat-stroke alerts remain active for Okinawa, western Japan, and the Pacific side of eastern Japan [1].
Forecasters said that the heat will intensify in other areas over the coming days. Kumamoto is expected to see increasingly dangerous temperatures as the weekend approaches [1].
"Maximum temperatures in western and eastern Japan are expected to be around 35 degrees Celsius," the Japan Meteorological Agency said [2].
“Kanto temperatures will rise between five and eight degrees Celsius compared to Tuesday.”
The simultaneous occurrence of a low-pressure system in the north and a high-pressure heat dome in the center illustrates the volatility of Japan's summer weather. The rapid temperature swing in the Kanto region—jumping up to eight degrees in 24 hours—can be particularly dangerous for the elderly and vulnerable, as the body has less time to acclimate to extreme heat, increasing the immediate risk of heat-stroke.
