A shift from north to south winds will bring clear skies and rising temperatures to the Kanto region on May 25 [1, 2].
This weather pattern marks a significant break from recent conditions, introducing a level of sunshine and heat that could trigger early summer precautions for residents in Tokyo and surrounding prefectures.
The Japan Meteorological Agency expects sunshine duration to exceed 10 hours on May 25 [1]. This will be the first day with such sunshine in the area in six days [1]. In Tokyo, the temperature forecast was 24.3°C on May 24 [1] and is expected to rise to 27°C on May 25 [1].
Other inland areas of Kanto, including Tochigi, Maebashi, and Kumagaya, are also expected to see daytime highs of 25°C or higher on May 25 [2]. The southerly flow is credited with increasing sunshine duration and raising temperatures across the region [1, 2].
The warming trend is expected to intensify toward the end of the month. Temperatures above 30°C are forecast for May 29 [1]. In some locations, such as Maebashi and Kumagaya, temperatures may reach as high as 33°C [1].
While the Kanto region prepares for this shift, other parts of the country are already experiencing extreme heat. A heat-stroke alert was issued for the Yaeyama region of Okinawa [1]. This represents the first nationwide heat-stroke alert of 2026 [1].
“Sunshine duration expected to exceed 10 hours on May 25”
The rapid transition from cool northern winds to warm southerly flows indicates an accelerated onset of summer temperatures in central Japan. With the first nationwide heat-stroke alert already triggered in Okinawa, the projected spike to 33°C in Kanto suggests that public health infrastructure may need to activate heat-warning protocols earlier than usual for the 2026 season.
