Heavy rain to hit South as monsoon strengthens over Thailand
Bangkok and surrounding provinces are set for afternoon-to-evening rain, while the southern west coast faces heavy rain and rougher seas.
- A strengthening southwest monsoon is causing heavy rain in Southern Thailand, with precipitation forecast over 70% of the region.
- The monsoon is expected to intensify from Thursday to Monday, bringing the potential for very heavy rain to the southern west coast.
- The public has been warned about the dangers of heavy rainfall, and vessels are advised to navigate with caution due to strong waves in the Andaman Sea.
The Thai Meteorological Department (TMD) warned in its forecast for Wednesday (May 27, 2026) that Bangkok and surrounding provinces could see rain during the evening commute, mainly from afternoon to evening, while the South would be affected by monsoon conditions, with thundershowers forecast over 70% of the southern west coast and heavy rain in some places.
For the next 24 hours, Thailand will see thundershowers, with isolated heavy rain along the southwestern coast, as a moderate southwest monsoon covers the Andaman Sea, Thailand, and the Gulf of Thailand.
People are advised to be aware of the dangers posed by heavy rain and accumulated rainfall during this period.
Winds and waves in the Andaman Sea and the Gulf of Thailand will be moderate.
Waves in the upper Andaman Sea will be about 2 metres high, while the lower Andaman Sea and the upper Gulf of Thailand will see waves of 1-2 metres.
In thundershower areas, waves will exceed 2 metres.
Vessels in these areas are advised to navigate with caution and avoid sailing in thundershower zones.
From Thursday (May 28, 2026) to Monday (June 1, 2026), Thailand will see more rain and isolated heavy rain, with very heavy rain in some areas of the East and the southern west coast.
This is because the monsoon trough will lie across upper Thailand, while the southwest monsoon covering the Andaman Sea, Thailand and the Gulf of Thailand will strengthen.
Waves in the Andaman Sea will also become stronger, with waves in the upper Andaman Sea 2-3 metres high and above 3 metres in thundershower areas.
Weather forecast for Thailand from 6am on Wednesday (May 27, 2026) to 6am on Thursday (May 28, 2026)
Bangkok and the surrounding provinces
- Thundershowers are expected in 30% of the area, mostly from afternoon to evening.
- Minimum temperature: 26-28 degrees Celsius
- Maximum temperature: 35-38 degrees Celsius
- Southwesterly winds: 10-20 kilometres per hour
The North
- Thundershowers are expected in 40% of the area, mostly in Mae Hong Son, Chiang Mai, Lamphun, Phayao, Nan, Uttaradit, Tak, Kamphaeng Phet, Phichit, Phitsanulok and Phetchabun.
- Minimum temperature: 22-26 degrees Celsius
- Maximum temperature: 34-37 degrees Celsius
- Southwesterly winds: 10-20 kilometres per hour
The Northeast
- Thundershowers are expected in 30% of the area, mostly in Loei, Nong Khai, Bueng Kan, Chaiyaphum, Khon Kaen, Kalasin, Maha Sarakham, Roi Et and Nakhon Ratchasima.
- Minimum temperature: 24-26 degrees Celsius
- Maximum temperature: 35-38 degrees Celsius
- Southwesterly winds: 10-20 kilometres per hour
The Central region
- Thundershowers are expected in 40% of the area, mostly in Nakhon Sawan, Uthai Thani, Lop Buri, Saraburi, Kanchanaburi, Ratchaburi, Nakhon Pathom and Samut Songkhram.
- Minimum temperature: 25-27 degrees Celsius
- Maximum temperature: 36-38 degrees Celsius
- Southwesterly winds: 10-20 kilometres per hour
The East
- Thundershowers are expected in 40% of the area, mostly in Nakhon Nayok, Prachin Buri, Rayong, Chanthaburi and Trat.
- Minimum temperature: 24-27 degrees Celsius
- Maximum temperature: 33-38 degrees Celsius
- Southwesterly winds: 15-35 kilometres per hour
- Waves will be 1-2 metres high, rising above 2 metres in thundershower areas.
The South East Coast
- Thundershowers are expected in 40% of the area, mostly in Chumphon, Surat Thani and Nakhon Si Thammarat.
- Minimum temperature: 23-26 degrees Celsius
- Maximum temperature: 34-36 degrees Celsius
- Southwesterly winds: 15-35 kilometres per hour. Waves will be about 1 metre high and 1-2 metres offshore, rising above 2 metres in thundershower areas.
The South, West Coast
- Thundershowers are expected in 70% of the area, with isolated heavy rain in Ranong, Phang Nga and Phuket.
- Minimum temperature: 23-26 degrees Celsius
- Maximum temperature: 31-34 degrees Celsius
- From Phang Nga northwards: southwesterly winds of 20-35 kilometres per hour. Waves will be about 2 metres high, rising above 2 metres in thundershower areas.
- From Phuket southwards: southwesterly winds of 15-35 kilometres per hour. Waves will be 1-2 metres high, rising above 2 metres in thundershower areas.
