TMD warns Thailand of heavy rain, 2–3m waves on Sept 25–27

The Thai Meteorological Department (TMD) issued its eighth warning at 5am Thai time on September 25, 2026, forecasting heavy to very heavy rain across parts of Thailand through September 27. Waves are expected to reach 2–3 metres in the upper Gulf of Thailand and upper Andaman Sea.

The TMD’s advisory No 8, reference 224/2569, forecasts heavy rain in many areas and very heavy downpours in some places on September 25–27. The affected regions are the North, lower Northeast, Central region including Bangkok and surrounding provinces, East and South.

TMD warns of flash floods near hills and in low-lying areas

The TMD warned that heavy downpours and continuing rainfall could trigger flash floods and torrents of water from the hills, particularly on foothill slopes near waterways and in low-lying areas.

Travellers should avoid routes repeatedly affected by flooding, especially low-lying roads where water could accumulate temporarily, the TMD advised. The department urged people across Thailand to plan daily activities and journeys carefully during September 25–27 to reduce potential harm and disruption.

Low-pressure system to move across lower Northeast and Central Thailand

A strong low-pressure system over eastern Thailand is expected to move across the lower Northeast and Central region, including Bangkok and surrounding provinces, along a monsoon trough over upper Thailand, according to the TMD.
The south-west monsoon over the Andaman Sea, southern Thailand and the Gulf of Thailand is also expected to strengthen, the TMD said.

Small boats in upper Gulf and upper Andaman Sea should stay ashore

Small boats in the upper Gulf of Thailand and upper Andaman Sea should remain ashore through September 27, the TMD advised. Mariners throughout the Gulf and Andaman Sea should navigate cautiously and avoid thunderstorms as winds and waves strengthen.

The TMD forecasts waves of 2–3 metres in the upper Gulf of Thailand and upper Andaman Sea during September 25–27, exceeding 3 metres in thunderstorms.

In the lower Gulf of Thailand and lower Andaman Sea, waves are forecast to reach around 2 metres, rising above 2 metres in thunderstorms during September 25–27, according to the TMD.

The TMD urged the public to follow further announcements and scheduled its next advisory for 5pm Thai time on September 25, 2026.

Weather updates from the TMD are available around the clock through the department’s website, or by calling 02-399-4012, 02-399-4013 or 1182.