Monsoon hits Bangkok as 70% rain forecast; TMD warns of heavy rain and floods

Thailand’s weather today, June 20, 2026, at 5pm: the Thai Meteorological Department has forecast that over the next 24 hours, the Central region, including Bangkok and surrounding provinces, the East and the South will see heavy rain in some areas.

The conditions are being caused by a moderate south-westerly monsoon still prevailing over the Andaman Sea, Thailand and the Gulf of Thailand, combined with a low-pressure cell covering upper Vietnam.

People in affected areas are advised to prepare for heavy rain and accumulated rainfall, which could trigger flash floods and forest run-off, especially in risk areas near waterways and low-lying areas.

Waves in the upper Andaman Sea are moderate at 1-2 metres high. In the lower Andaman Sea and the Gulf of Thailand, waves are around one metre high. In thunderstorm areas, waves may rise above two metres.

Boat operators in the Andaman Sea and the Gulf of Thailand are advised to navigate with caution and avoid sailing in thunderstorm areas.

Weather forecast from 6pm today to 6pm tomorrow

Bangkok and surrounding provinces

• Thunderstorms are expected in 70% of the area, with heavy rain in some places.
• Minimum temperature: 25-27°C
• Maximum temperature: 32-35°C
• South-westerly winds: 10-20 km/h

Northern region

• Thunderstorms are expected in 40% of the area, mostly in Mae Hong Son, Chiang Mai, Chiang Rai, Lampang, Phayao, Nan, Tak, Kamphaeng Phet and Phetchabun.
• Minimum temperature: 23-26°C
• Maximum temperature: 32-36°C
• South-westerly winds: 10-20 km/h

Northeastern region

• Thunderstorms are expected in 40% of the area, mostly in Loei, Nong Khai, Bueng Kan, Nong Bua Lamphu, Udon Thani, Sakon Nakhon, Nakhon Phanom, Chaiyaphum, Nakhon Ratchasima and Buri Ram.
• Minimum temperature: 24-26°C
• Maximum temperature: 33-36°C
• South-westerly winds: 10-20 km/h

Central region

• Thunderstorms are expected in 60% of the area, with heavy rain in some places, especially in Phra Nakhon Si Ayutthaya, Saraburi, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Songkhram and Samut Sakhon.
• Minimum temperature: 23-26°C
• Maximum temperature: 34-36°C
• South-westerly winds: 10-20 km/h

Eastern region

• Thunderstorms are expected in 60% of the area, with heavy rain in some places, especially in Nakhon Nayok, Chachoengsao, Chon Buri, Rayong, Chanthaburi and Trat.
• Minimum temperature: 23-26°C
• Maximum temperature: 32-34°C
• South-westerly winds: 15-30 km/h
• Waves around one metre high, and above two metres in thunderstorm areas.

Southern region, east coast

• Thunderstorms are expected in 60% of the area, with heavy rain in some places, especially in Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani, Yala and Narathiwat.
• Minimum temperature: 23-25°C
• Maximum temperature: 32-36°C
• South-westerly winds: 15-30 km/h
• Waves around one metre high, and above two metres in thunderstorm areas.

Southern region, west coast

• Thunderstorms are expected in 70% of the area, with heavy rain in some places, especially in Ranong, Phang Nga, Phuket, Krabi, Trang and Satun.
• Minimum temperature: 23-26°C
• Maximum temperature: 32-34°C
• From Phuket northwards: south-westerly winds of 15-35 km/h. Waves 1-2 metres high, and above two metres in thunderstorm areas.
• From Krabi southwards: south-westerly winds of 15-30 km/h. Waves around one metre high, and above two metres in thunderstorm areas.