Japan is facing a divide of extreme weather today, with dangerous heat in the south and heavy rain risks in the north [1, 2].
These contrasting conditions create simultaneous public health and safety risks across the archipelago, ranging from heatstroke in Kyushu to potential flash flooding in northern prefectures.
In Kyushu and other southern regions, temperatures are expected to reach dangerous levels, approaching 40°C [2]. Fukuoka is specifically predicted to reach a high of 38°C [2]. This heat wave is linked to an approaching atmospheric system that is pushing extreme temperatures into the region [2].
Meanwhile, northern Japan, including Hokkaido and Tohoku, faces a risk of very heavy rain [1, 2]. Forecasters said that these rains could be intense enough to flood roads in localized areas [1, 2]. This risk is attributed to cold air aloft and specific atmospheric conditions [2]. Thunderstorms are also expected to impact northern and eastern Japan [1].
Temperature forecasts for other major cities show a steady climb toward the coast. Tokyo is expected to reach 31°C [2], while Osaka will see 33°C [2]. In the north, Sendai and Niigata are both predicted to hit 28°C [2]. Sapporo is forecast at 27°C [2], Aomori at 26°C [2], Morioka at 25°C [2], and Kushiro at 22°C [2].
Other regional updates include the official end of the rainy season for Shikoku [1, 2]. While western Japan is expected to remain sunny, residents in mountainous areas should be alert for sudden rainfall [1]. Additionally, officials said that Okinawa should monitor for high waves [1].
“Kyushu and other regions are expected to experience dangerously hot temperatures approaching 40°C”
The simultaneous occurrence of extreme heat and heavy rain highlights the volatility of Japan's summer transition. The end of the rainy season in Shikoku marks a seasonal shift, but the persistence of high-temperature systems in the south and unstable air in the north suggests a high-risk period for both infrastructure and public health.
