The Japan Meteorological Agency said that the Hokuriku and southern Tohoku regions entered the rainy season on the morning of June 20 [1, 2].
This transition marks the beginning of a period of sustained precipitation that can lead to significant infrastructure damage and public safety risks. The agency is warning residents of landslides, river swelling, and road flooding as a north-moving rainy-front advances across the country [1, 3, 4].
Weather officials forecast localized intense thunderstorms for the morning of June 21 [1, 2]. Expected rainfall totals for that day include up to 150 mm in the Tokai region, 120 mm in Hokuriku, and 100 mm in Kanto-Koshin [1].
The arrival of the season occurred later than usual for both areas. Hokuriku entered the rainy season nine days later than the average [2], while southern Tohoku entered eight days later than the average [2].
Atmospheric instability is expected to produce the severe weather. Meteorologist Junko Miyake said that the weather is likely to change abruptly this afternoon [2].
The Japan Meteorological Agency said that Hokuriku and southern Tohoku appear to have entered the rainy season [1]. The agency continues to monitor the rainy-front as it moves north, bringing cloudiness and precipitation to a broad area stretching from Kyushu to Kanto-Koshin [1, 3].
“Hokuriku and southern Tohoku entered the rainy season on the morning of June 20”
The delayed onset of the rainy season in Hokuriku and southern Tohoku may alter typical agricultural cycles and water management strategies. However, the forecast for intense, localized rainfall—reaching 150 mm in some areas—increases the immediate risk of flash flooding and landslides, which are common hazards during Japan's transition into the summer monsoon period.
