The Meteorological Agency announced Tuesday that the Kanto-Koshin and Hokuriku regions have “likely entered the rainy season,” marking the beginning of sustained wet weather across most of the country.
The declaration follows Monday’s announcement for the Tokai, Kinki, and Chugoku regions. The northern Kyushu and Shikoku regions entered the rainy season on Sunday while the season ended in Okinawa the same day, the agency said. Southern Kyushu’s rainy season began unusually early, on May 16.
The seasonal rain front is forecast to linger over Honshu, bringing repeated rounds of rainfall to both western and eastern Japan. It is expected to remain especially active through Wednesday, with heavy rain likely in areas including Kanto-Koshin and Hokuriku. Western Japan faces a particularly high risk of torrential downpours.
While the front may temporarily weaken after Wednesday, forecasters expect it to strengthen again around Saturday, coinciding with the likely start of the rainy season in the Tohoku region.
On Tuesday morning, northern Kyushu saw especially intense rain, prompting the Meteorological Agency to warn of a potential linear rainband forming later in the day.
In the 24 hours through 6 a.m. Wednesday, up to 180 millimeters of rain is forecast in northern Kyushu, 150 mm in the Kinki region, and 120 mm across Chugoku and southern Kyushu.
Between 6 a.m. Wednesday and 6 a.m. Thursday, up to 60 mm of rain is expected in northern Kyushu.
With the seasonal rains now in full swing, authorities are urging residents to remain on alert for landslides, river overflows, and flooding in low-lying areas such as underpasses. Officials recommend preparing emergency supplies, confirming multiple evacuation routes that avoid flood-prone zones, and clearing gutters and drains of debris to reduce risk before heavy rainfall begins.
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