Monsoon warning puts Thailand on alert for rain, floods and high waves
The Thai Meteorological Department has warned of heavier rain across Thailand, with flash floods possible and waves above 3 metres in the Andaman.
- Thailand's Meteorological Department has issued a warning for heavy to very heavy rain across 60-70% of the country, driven by a strong southwest monsoon.
- The public is alerted to the risk of flash floods and forest run-off, with 56 provinces placed under special monitoring.
- High waves are forecast for the Andaman Sea, expected to reach 2-3 meters and potentially exceed 3 meters in thunderstorms, prompting a warning for small boats to remain ashore.
The Thai Meteorological Department warned on Friday (May 29, 2026) that thunderstorms were forecast across an average of 60-70% of areas nationwide, with heavy to very heavy rain expected in some places, as a rather strong southwest monsoon covers the Andaman Sea, Thailand and the Gulf of Thailand, while a monsoon trough also influences conditions.
The department also listed 56 provinces for special monitoring due to thunderstorms, warning the public to watch for floodwater, flash floods and forest run-off.
In the Andaman Sea, waves could exceed 3 metres, while small boats have been advised to remain ashore.
In its 24-hour forecast, the Thai Meteorological Department said rainfall would increase across Thailand, with isolated heavy rain and very heavy rain in some areas of the South’s west coast.
The conditions are being driven by a rather strong southwest monsoon prevailing over the Andaman Sea, Thailand and the Gulf of Thailand, while a monsoon trough lies across upper Laos into a low-pressure cell over the South China Sea.
People across Thailand are advised to prepare for heavy to very heavy rain and accumulated rainfall, which could trigger flash floods and forest run-off, especially in risk areas near waterways and in low-lying zones.
Winds and waves in the upper Andaman Sea, from Phuket northward, are rather strong, with waves of 2-3 metres and more than 3 metres in thundershowers.
In the lower Andaman Sea, from Krabi southward, waves are about 2 metres high, while the upper Gulf of Thailand has waves of 1-2 metres and more than 2 metres in thundershowers.
Mariners are advised to navigate with caution and avoid sailing in areas with thundershowers.
Small boats in the upper Andaman Sea should remain ashore during this period.
Weather forecast for Thailand from 6am on Friday (May 29, 2026), to 6am on Saturday (May 30, 2026)
North
- Thunderstorms are forecast over 60% of the region, with isolated heavy rain in Mae Hong Son, Chiang Mai, Lamphun, Lampang, Nan, Uttaradit, Sukhothai, Kamphaeng Phet, Phichit, Phitsanulok, Phetchabun and Tak.
- Low: 22-25°C
- High: 35-38°C
- Southwesterly winds: 10-20 km/h
Northeast
- Thunderstorms are forecast over 60% of the region, with isolated heavy rain in Nong Khai, Bueng Kan, Sakon Nakhon, Nakhon Phanom, Chaiyaphum, Mukdahan, Maha Sarakham, Roi Et, Yasothon, Amnat Charoen, Nakhon Ratchasima, Buri Ram, Surin, Si Sa Ket and Ubon Ratchathani.
- Low: 23-25°C
- High: 36-38°C
- Southwesterly winds: 10-20 km/h
Central region
- Thunderstorms are forecast over 60% of the region, mostly in Kanchanaburi, Uthai Thani, Saraburi, Phra Nakhon Si Ayutthaya, Suphan Buri, Ratchaburi, Nakhon Pathom and Samut Sakhon.
- Low: 23-26°C
- High: 35-39°C
- Southwesterly winds: 10-20 km/h
East
- Thunderstorms are forecast over 60% of the region, with isolated heavy rain in Nakhon Nayok, Chachoengsao, Chonburi, Rayong, Chanthaburi and Trat.
- Low: 24-27°C
- High: 32-37°C
- Southwesterly winds: 15-35 km/h
- Waves: 1-2 metres, rising above 2 metres in thundershowers
South, east coast
- Thunderstorms are forecast over 60% of the region, with isolated heavy rain in Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani and Nakhon Si Thammarat.
- Low: 23-25°C
- High: 34-36°C
- Southwesterly winds: 15-35 km/h
- Waves: about 1 metre, 1-2 metres offshore, and above 2 metres in thundershowers
South, west coast
- Thunderstorms are forecast over 70% of the region, with isolated heavy to very heavy rain in Ranong, Phang Nga, Phuket and Krabi.
- Low: 24-27°C
- High: 29-35°C
- From Phuket northward: southwesterly winds of 20-40 km/h. Waves are 2-3 metres, rising above 3 metres in thundershowers.
- From Krabi southward: southwesterly winds of 20-35 km/h. Waves are about 2 metres, rising above 2 metres in thundershowers.
Bangkok and the surrounding provinces
- Thunderstorms are forecast over 60% of the area, with isolated heavy rain, mostly from the afternoon to evening.
- Low: 26-27°C
- High: 33-37°C
- Southwesterly winds: 10-20 km/h
