Heavy rain and possible flash floods forecast across Thailand
Very heavy rain is forecast in the East and on the southern west coast, with flash floods and rough seas possible between Sunday and Thursday.
- The Thai Meteorological Department has issued a warning for heavy to very heavy rain across Thailand from Sunday, July 26 to Thursday, July 30.
- The intense rainfall may cause flash floods and run-off, particularly in areas on foothill slopes and in low-lying regions.
- The weather is caused by a monsoon trough combined with a strengthened southwest monsoon over the Andaman Sea and the Gulf of Thailand.
- Mariners are also warned of strong winds and waves of 2-3 meters, with small boats in the upper Andaman Sea advised to remain ashore.
The Thai Meteorological Department (TMD) issued a warning at 5pm on Thursday (July 23, 2026) of heavy to very heavy rain in Thailand from Sunday (July 26, 2026) to Thursday (July 30, 2026), with possible flash floods and run-off from forested areas.
The department said isolated heavy rain was forecast across Thailand during the period, with isolated very heavy rain in the East and along the southern west coast.
The conditions would be caused by a monsoon trough across the upper North, Laos and upper Vietnam, together with a southwest monsoon that would strengthen over the Andaman Sea, Thailand and the Gulf of Thailand.
People were advised to beware of the dangers posed by heavy to very heavy rain and accumulated rainfall, which could cause flash floods and run-off from forested areas, particularly on foothill slopes near waterways and in low-lying areas.
Wind and waves in the upper Andaman Sea are expected to be rather strong, with waves 2-3 metres high and above 3 metres in thunderstorms.
In the upper Gulf of Thailand and lower Andaman Sea, waves are forecast at about 2 metres, rising above 2 metres in thunderstorms.
Mariners in the Andaman Sea and Gulf of Thailand were advised to navigate with caution and avoid sailing in areas affected by thunderstorms.
Small boats in the upper Andaman Sea should remain ashore during the period.
A tropical depression over the Pacific Ocean is expected to intensify into a tropical storm and move across the northern Philippines into the northern South China Sea from July 24 to 25.
It is then forecast to make landfall in Guangdong province, China, from July 26 to 27.
The storm is not expected to enter Thailand.
Travellers planning to visit those areas during the period were advised to check weather conditions before departure.
To ensure safety and minimise possible impacts, the department urged people to plan their daily activities and journeys carefully during the period and follow its announcements.
Information is available on the department’s website at http://www.tmd.go.th or by calling 0-2399-4012-13 or 1182, 24 hours a day.
