Strong monsoon brings heavy rain and rough seas across Thailand

The Thai Meteorological Department (TMD) forecast for Thursday (June 4, 2026) warned that a fairly strong monsoon is covering Thailand.

Bangkok and surrounding provinces are expected to see thundershowers over 60% of the area and isolated heavy rain, while the South will face strong waves.

For the next 24 hours, upper Thailand will see more rain and isolated heavy rain, with very heavy rain in some areas in the west of the Central region, the East, and the west coast of the South.

This is due to a fairly strong southwest monsoon prevailing over the Andaman Sea, Thailand and the Gulf of Thailand.

People in these areas are advised to prepare for heavy to very heavy rain and accumulated rainfall, which could trigger flash floods and runoff, especially in risk areas near waterways and in low-lying areas.

Waves in the Andaman Sea and the upper Gulf of Thailand are fairly strong, reaching 2-3 metres and rising above 3 metres in thundershowers.

Mariners in the Andaman Sea and the Gulf of Thailand are advised to navigate with caution and avoid sailing in thundershower areas.

Small boats in the Andaman Sea and the upper Gulf of Thailand should stay ashore for the time being.

Weather forecast for Thailand from 6am Thursday (June 4) to 6am Friday (June 5)

Bangkok and the surrounding provinces

• Thundershowers are expected over 60% of the area, with isolated heavy rain.
• Minimum temperature: 26-27 degrees Celsius
• Maximum temperature: 32-33 degrees Celsius
• Southwesterly winds: 10-20km/h

North

• Thundershowers are expected over 60% of the area, with isolated heavy rain in Mae Hong Son, Tak, Phayao, Phrae, Nan, Kamphaeng Phet, Phitsanulok and Phetchabun.
• Minimum temperature: 22-27 degrees Celsius
• Maximum temperature: 34-38 degrees Celsius
• Southwesterly winds: 10-20km/h

Northeast

• Thundershowers are expected over 40% of the area, with isolated heavy rain in Loei, Nong Khai, Bueng Kan, Sakon Nakhon, Nakhon Phanom, Chaiyaphum and Nakhon Ratchasima.
• Minimum temperature: 24-26 degrees Celsius
• Maximum temperature: 34-35 degrees Celsius
• Southwesterly winds: 10-20km/h

Central region

• Thundershowers are expected over 60% of the area, with isolated heavy to very heavy rain in Nakhon Sawan, Uthai Thani, Kanchanaburi, Ratchaburi, Suphan Buri, Nakhon Pathom, Samut Songkhram, Samut Sakhon, Phra Nakhon Si Ayutthaya, Lop Buri and Saraburi.
• Minimum temperature: 25-27 degrees Celsius
• Maximum temperature: 34-35 degrees Celsius
• Southwesterly winds: 10-20km/h

East

• Thundershowers are expected over 70% of the area, with isolated heavy to very heavy rain in Nakhon Nayok, Prachin Buri, Chachoengsao, Chon Buri, Rayong, Chanthaburi and Trat.
• Minimum temperature: 24-28 degrees Celsius
• Maximum temperature: 31-34 degrees Celsius
• Southwesterly winds: 20-40km/h
• Waves will be 2-3 metres high and more than 3 metres in thundershowers.

South (east coast)

• Thundershowers are expected over 60% of the area, with isolated heavy rain in Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani and Nakhon Si Thammarat.
• Minimum temperature: 24-27 degrees Celsius
• Maximum temperature: 30-35 degrees Celsius
• From Surat Thani northward: Southwesterly winds at 20-40km/h. Waves will be 1-2 metres high and more than 2 metres offshore and in thundershowers.
• From Nakhon Si Thammarat southward: Southwesterly winds at 20-35km/h. Waves will be 1-2 metres high, about 2 metres offshore and more than 2 metres in thundershowers.

South (west coast)

• Thundershowers are expected over 70% of the area, with isolated heavy to very heavy rain in Ranong, Phang Nga, Phuket, Krabi, Trang and Satun.
• Minimum temperature: 23-25 degrees Celsius
• Maximum temperature: 28-34 degrees Celsius
• Southwesterly winds: 20-40km/h
• Waves will be 2-3 metres high and more than 3 metres in thundershowers.