Thailand warns 54 provinces of heavy to very heavy rain

The Thai Meteorological Department (TMD) has issued its seventh warning on heavy to very heavy rain across Thailand and strong waves in the Andaman Sea, with the impact expected to last until May 18, 2026.

TMD Director-General Sugunyanee Yavinchan issued Announcement No. 7, or 67/2026, at 5am on May 16, warning that Thailand will see more rain, with heavy to very heavy falls in some parts of the North, Central region, East and South.

People in affected areas have been urged to beware of heavy to very heavy rainfall and accumulated rain, which could trigger flash floods and forest run-off, especially on foothill slopes near waterways and in low-lying areas.

The department said the conditions are being driven by a stronger south-westerly monsoon covering the Andaman Sea, Thailand and the Gulf of Thailand. People have also been advised to take care of their health during changing weather conditions.

Strong waves in the Andaman Sea

Waves in the Andaman Sea and the Gulf of Thailand are expected to become rather strong.

In the upper Andaman Sea, from Phuket northwards, waves are forecast at 2-3 metres, rising above 3 metres in thundershowers.

In the lower Andaman Sea, from Krabi southwards, and the upper Gulf of Thailand, waves are expected to be around 2 metres, rising above 2 metres in thundershowers.

Boat operators have been advised to proceed with caution and avoid areas with thundershowers. Small boats in the upper Andaman Sea should remain ashore.

The public has been urged to follow further announcements from the Thai Meteorological Department. The next announcement is scheduled for 5pm on May 16.

Risk areas on May 16

For May 16, areas at risk of very heavy rain are:

• North: Mae Hong Son, Chiang Mai, Chiang Rai and Tak.
• Northeast: Bueng Kan, Amnat Charoen and Ubon Ratchathani.

Areas at risk of heavy rain are:

• North: Lamphun, Lampang, Phayao, Nan, Phrae, Uttaradit, Phitsanulok, Phichit, Phetchabun, Sukhothai and Kamphaeng Phet.
• Northeast: Loei, Sakon Nakhon, Nakhon Phanom, Chaiyaphum, Kalasin, Mukdahan, Yasothon, Amnat Charoen, Nakhon Ratchasima and Ubon Ratchathani.
• Central region: Nakhon Sawan, Uthai Thani, Chai Nat, Sing Buri, Lop Buri, Saraburi, Kanchanaburi, Suphan Buri, Nakhon Pathom and Ratchaburi.
• East: Chon Buri, Rayong, Chanthaburi and Trat.
• South: Prachuap Khiri Khan, Chumphon, Surat Thani, Songkhla, Pattani, Yala, Narathiwat, Ranong, Phang Nga, Krabi, Trang and Satun.

Risk areas on May 17

For May 17, areas at risk of very heavy rain are:

• Central region: Kanchanaburi and Ratchaburi.
• East: Rayong, Chanthaburi and Trat.
• South: Phetchaburi, Prachuap Khiri Khan, Chumphon, Ranong and Phang Nga.

Areas at risk of heavy rain are:

• North: Mae Hong Son, Chiang Mai, Tak, Kamphaeng Phet, Phichit, Phitsanulok and Phetchabun.
• Northeast: Loei, Nong Khai, Nong Bua Lamphu, Udon Thani, Bueng Kan, Sakon Nakhon, Nakhon Phanom, Chaiyaphum and Nakhon Ratchasima.
• Central region: Nakhon Sawan, Uthai Thani, Chai Nat, Sing Buri, Ang Thong, Lop Buri, Saraburi, Phra Nakhon Si Ayutthaya, Suphan Buri, Nakhon Pathom, Samut Songkhram and Samut Sakhon, including Bangkok and surrounding provinces.
• East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao and Chon Buri.
• South: Surat Thani, Nakhon Si Thammarat, Phuket, Krabi, Trang and Satun.

Risk areas on May 18

For May 18, areas at risk of very heavy rain are:

• North: Tak and Kamphaeng Phet.
• Central region: Nakhon Sawan, Uthai Thani, Suphan Buri, Kanchanaburi and Ratchaburi.
• East: Chanthaburi and Trat.
• South: Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Ranong, Phang Nga, Phuket and Krabi.

Areas at risk of heavy rain are:

• North: Mae Hong Son, Chiang Mai, Lamphun, Lampang, Sukhothai, Phrae, Uttaradit, Phichit, Phitsanulok and Phetchabun.
• Northeast: Loei, Nong Khai, Nong Bua Lamphu, Bueng Kan, Udon Thani, Sakon Nakhon, Nakhon Phanom, Chaiyaphum, Khon Kaen, Kalasin, Maha Sarakham, Mukdahan and Nakhon Ratchasima.
• Central region: Chai Nat, Sing Buri, Ang Thong, Lop Buri, Saraburi, Phra Nakhon Si Ayutthaya, Nakhon Pathom, Samut Songkhram and Samut Sakhon, including Bangkok and surrounding provinces.
• East: Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chon Buri and Rayong.
• South: Nakhon Si Thammarat, Phatthalung, Songkhla, Trang and Satun.

Thailand officially entered the 2026 rainy season on May 15, with rainfall forecast to be around 10% below normal overall and one to two tropical storms expected to affect the country during the season. The latest heavy-rain warning follows several days of alerts over stronger monsoon conditions, flash-flood risk and rough seas in the Andaman.