Bangkok: The Meteorological Department has issued its fifth bulletin, announcing expectations of heavy to very heavy rainfall across Thailand from September 9 to 13, 2026.

According to Thai News Agency, the North, Northeast, Central, and Eastern regions are particularly susceptible to this weather pattern due to a high-pressure system or cold air mass spreading over Vietnam and upper Laos. This system is causing the monsoon trough to move southward, impacting the North, upper Central, and Northeast regions. Additionally, a moderate southwest monsoon is affecting the Andaman Sea, Thailand, and the Gulf of Thailand, with predictions indicating this will persist from September 10-13, 2026.

The announcement highlights that the lower northeastern region, the central region including Bangkok and its surrounding areas, the eastern region, and the southern region will continue to experience rainfall, with some areas facing heavy to very heavy rain. This is attributed to a high-pressure system or cold air mass from China spreading over the upper northern and upper northeastern regions, shifting the monsoon trough southward. This shift is expected to pass through the lower central, lower northeastern, and eastern regions, and into a strong low-pressure system in the central South China Sea. The southwest monsoon affecting the Andaman Sea, the southern region, and the Gulf of Thailand is also expected to strengthen.

Residents in upper and upper southern Thailand are urged to be cautious of the dangers posed by heavy to very heavy rainfall and accumulated rainfall, which could lead to flash floods and landslides. Those living near slopes, waterways, and low-lying areas should avoid traveling on routes prone to flooding, particularly in areas susceptible to short-term flooding.

The bulletin also notes the likelihood of a low-pressure system in the central South China Sea intensifying into a tropical cyclone between September 11-13, 2026. The public is advised to stay informed by monitoring weather forecasts during this period.

For safety and to minimize potential impacts during this period, the public is encouraged to plan their daily activities and travel with caution and to adhere to announcements from the Meteorological Department.