The Japan Meteorological Agency forecast temperatures around 30 °C in many regions on June 12, 2024, with a mix of sunny skies and severe storms [1].
This weather pattern creates a stark divide across the archipelago, where some residents face intense summer heat while others deal with hazardous atmospheric instability. The disparity highlights the volatile nature of the rainy season as weather fronts shift across the islands.
Sunny conditions are expected across northern Kyushu, Shikoku, Chugoku, Kinki, Tokai, and Tohoku [1]. In these areas, temperatures are projected to climb. Nagoya and Okayama are forecast to reach 31 °C [1]. Osaka, Hiroshima, and Naha are expected to hit 30 °C [1]. Morioka is also forecast at 30 °C [1].
Other regions will see milder highs. Kanazawa is forecast at 29 °C, while Kochi is expected to reach 29 °C [1]. Nagano, Fukuoka, and Kagoshima are each forecast at 28 °C [1]. Matsue is expected to hit 27 °C [1]. Sendai and Niigata are both forecast at 26 °C [1]. Aomori is projected at 25 °C [1]. In the north, Sapporo is forecast at 22 °C and Kushiro at 17 °C [1].
Conversely, the Kanto-Koshin area, including Tokyo, will continue to experience rainy conditions and thunderstorms [1]. Tokyo's forecast high is 25 °C [1]. Forecasters said this is due to moist air and upper-level cold air creating atmospheric instability.
Southern Kyushu faces the most severe risks. The agency said there is a risk of intense thunderstorms in the region, specifically mentioning areas such as Tanegashima and Yakushima [1]. This is because the rain clouds of the rainy-season front are lingering in the south [2].
Weather forecasters said the rainy-season front has moved south of the main islands, which is why many regions are now seeing clear skies [2].
“The Japan Meteorological Agency forecast temperatures around 30 °C in many regions”
The movement of the rainy-season front south of the main islands typically signals a transition toward summer heat for central and northern Japan. However, the lingering instability in the Kanto-Koshin and southern Kyushu regions demonstrates how localized atmospheric clashes, between moist tropical air and cold upper-level currents, can sustain dangerous storm cells even as other regions experience a heatwave.
