Japan Issues Level 5 Flood Warning for Koyoshi River, Confirms Overflow at Yurihonjo

Japan's weather agency, JMA, issued a Level 5 flood special warning (the top of its five-level scale, reserved for when a disaster has very likely already occurred) for the Koyoshi River in Akita Prefecture at 11:09 p.m. local time (2:09 p.m. UTC) on Oct. 21, 2026. The agency said the river had already overflowed near Morishi, in the city of Yurihonjo.

JMA said a disaster has very likely already occurred in flood-risk zones along the river, a situation that corresponds to its Level 5 alert, and that people there faced imminent danger to life and needed to secure their safety immediately. The agency told residents already under local evacuation orders to follow them without delay and, because the warning came at night, to check their surroundings carefully before moving.

The Mainichi reported no injuries so far, as of Oct. 21, 2026.