Heavy rain shifts south across Thailand, flash-flood warning runs through September 13
Bangkok and the South face continued downpours on September 10–13, while a South China Sea low-pressure area could develop into a tropical cyclone
Residents in upper Thailand and the upper South have been warned of flash floods and rapid run-off during September 9–13, particularly on foothill slopes near waterways and in low-lying areas.
The Thai Meteorological Department (TMD) issued its fifth heavy-rain advisory, numbered 195/2569, at 5am Thai time on Wednesday (September 9, 2026).
It warned that heavy to very heavy downpours and accumulated rainfall could cause flooding.
On September 9, isolated heavy to very heavy rain is forecast, particularly in the North, Northeast, Central region and East.
A high-pressure system, or cool air mass, spreading over Vietnam and upper Laos has pushed the monsoon trough southwards across the North, upper Central region and Northeast.
A moderate southwest monsoon is also covering the Andaman Sea, Thailand and the Gulf of Thailand.
Rain continues farther south from September 10
During September 10–13, rain is expected to continue in the lower Northeast, Central region including Bangkok and surrounding provinces, East and South, with heavy to very heavy falls in some areas.
Rainfall will decrease in the North and upper Northeast.
A high-pressure system from China is forecast to extend over the upper North and upper Northeast, pushing the monsoon trough farther south across the lower Central region, lower Northeast and East, into a strong low-pressure area over the central South China Sea.
The southwest monsoon over the Andaman Sea, southern Thailand and the Gulf of Thailand will also strengthen.
Avoid flood-prone roads and follow storm updates
The department advised residents to avoid routes repeatedly affected by flooding, particularly low-lying roads where water could accumulate temporarily.
People should plan daily activities and journeys carefully during the warning period to reduce danger and disruption.
A low-pressure area over the central South China Sea could develop into a tropical cyclone, the department said, urging continued monitoring during September 11–13.
Weather updates are available through the TMD website and its 24-hour telephone services on 02-399-4012, 02-399-4013 and 1182.
The next advisory was scheduled for 5pm on September 9.
