Thailand's Office of National Water Resources issued Alert No. 5/2569 for September 22–26, warning of heavy rainfall, flash floods, and flash runoff across multiple regions due to a deepening low-pressure system moving into Thailand along the monsoon trough. The Chao Phraya River is expected to discharge ~1,500 cubic meters per second, raising downstream water levels by 0.75–1.25 meters and threatening flood-prone areas in Chai Nat, Sing Buri, Ang Thong, Ayutthaya, and Pathum Thani. Authorities are urged to monitor rainfall, manage water releases from dams coordinated upstream to downstream, accelerate drainage, and warn residents in at-risk areas to evacuate in time.