The Japan Meteorological Agency announced the start of the rainy season for northern Tohoku on Sunday morning [1].
This transition brings a dual threat to the region: the risk of flooding from heavy precipitation and a spike in heat-stroke cases due to high humidity. The timing of the onset is atypical for the region, potentially disrupting agricultural schedules and local infrastructure preparations.
According to the agency, the arrival of the rainy season in northern Tohoku was six days later than the average year [1]. The delay follows a period of fluctuating weather patterns that have kept the region drier than usual for the month of June.
Heavy rainfall is now expected across the north. Forecasters said that some areas in Miyagi Prefecture could see 24-hour rainfall exceeding 100 millimeters [1]. An additional 120 millimeters of rain is forecast through Monday [1].
While the north prepares for floods, other parts of the country are facing extreme heat. The agency issued warnings for western and eastern Japan, where high temperatures combined with humidity are increasing the risk of heat-stroke [2].
Specific urban centers are expected to reach peak temperatures. Highs of 33 degrees Celsius are forecast for Kofu, Nagoya, and Kochi [1]. Authorities said that the combination of heat and humidity makes it necessary to take precautions against heat-related illnesses [2].
Local residents are advised to monitor weather updates closely as the rainy front moves across the archipelago. The agency said that the increased humidity will make the heat feel more intense, further elevating the health risks for elderly populations, and outdoor workers [2].
“The arrival of the rainy season in northern Tohoku was six days later than the average year.”
The delayed onset of the rainy season in northern Tohoku, coupled with extreme heat in the south and center of Japan, suggests a volatile atmospheric pattern. The concentration of heavy rainfall in Miyagi Prefecture poses immediate risks of landslides and urban flooding, while the simultaneous heat-stroke warnings across western and eastern Japan indicate a dangerous transition into the peak summer months.
