TMD warns of heavy rain and 2–3m waves until September 27
Thailand’s weather warning covers Bangkok and several regions, with small boats in the upper Gulf and upper Andaman Sea advised to stay ashore
- The Thai Meteorological Department (TMD) has issued a warning for heavy to very heavy rain across many regions of Thailand, including Bangkok, effective until September 27.
- Waves in the upper Gulf of Thailand and upper Andaman Sea are forecast to be 2–3 metres high, exceeding three metres during thunderstorms.
- The heavy rainfall creates a risk of flash floods, and small boats in the upper Gulf and Andaman Sea are advised to remain ashore.
The Thai Meteorological Department (TMD) issued a warning at 5am Thai time on Thursday (September 24, 2026) for heavy to very heavy rain and possible flash floods in parts of Thailand through September 27.
Heavy rain forecast across Bangkok and several regions
The TMD’s sixth warning, numbered 222/2569, forecasts heavy rain in many areas and very heavy rain in some places during September 24–27. Affected regions include the North, lower Northeast, Central region including Bangkok and surrounding provinces, East and South.
The TMD attributed the forecast to a strong low-pressure system over Cambodia that is expected to move across the lower Northeast, East and Central region, including Bangkok and surrounding provinces, along a monsoon trough over upper Thailand.
The south-west monsoon over the Andaman Sea, Thailand and the Gulf of Thailand is also expected to strengthen, according to the TMD.
TMD warns of flash floods near hills and waterways
The TMD warned that heavy to very heavy rain and the continued accumulation of rainfall could trigger flash floods and torrents of water from the hills, particularly on foothill slopes near waterways and in low-lying areas.
The TMD advised people to avoid routes prone to repeated flooding, especially low-lying roads where water could accumulate temporarily. Residents should also plan daily activities and journeys carefully during the warning period to stay safe and reduce potential disruption.
Stronger winds and higher waves forecast in both seas
The TMD expects winds and waves to strengthen in the Gulf of Thailand and the Andaman Sea, with sea conditions forecast as follows:
Upper Gulf of Thailand and upper Andaman Sea: Waves of 2–3 metres, exceeding three metres during thunderstorms.
Lower Gulf of Thailand and lower Andaman Sea: Waves of around two metres, exceeding two metres during thunderstorms.
The TMD advised mariners in the Gulf of Thailand and the Andaman Sea to navigate with caution and avoid areas affected by thunderstorms. Small boats in the upper Gulf and upper Andaman Sea should remain ashore until September 27.
The TMD urged the public to follow its announcements. Weather information is available around the clock through the department’s website or by calling 02-399-4012, 02-399-4013 or 1182.
The TMD said its next warning would be issued at 5pm on September 24.
