The Tokyo metropolitan area is expected to see torrential rain on Friday night, with western Japan having already seen the arrival of heavy rain storms, Weathernews said Friday.
Weathernews said the heavy rainfall was predicted across much of Japan, from Kyushu to the Kanto region, which encompasses seven prefectures: Chiba, Gunma, Ibaraki, Kanagawa, Saitama, Tochigi and Tokyo.
Rain started falling early in the morning in the Tokyo metropolitan area, with precipitation reaching 6.5 millimeters per hour by 11 a.m. in Tateyama, Chiba Prefecture.
Weathernews warned that it will likely continue to rain through Saturday morning and urged local residents to be on alert for possible floods, landslides and swelling rivers. According to the forecast, some places may experience torrential rain of up to 30 to 50 mm per hour, which could result in flooded roads.
Japan's rainy season normally starts between May and July, depending on the region. But this year, it has started earlier than usual in southern Japan, with Okinawa Prefecture entering the rainy season on May 4 — six days earlier than the average year. The rain front is expected to move northward to the Honshu area from late May to mid-June.
This year’s rainy season is also expected to end earlier than average, with total rainfall predicted to be the same. According to Weathernews, peak rainfall is expected in late May in Okinawa, between late June and early July in the Kyushu, Chugoku, and Shikoku regions, and in late June in the Kansai and Kanto regions.