Monsoon brings heavy rain to 70% of Thailand, thunderstorms in Bangkok

Residents are urged to be on alert for flash floods and run-off, particularly in foothill zones, near waterways, and low-lying areas.

The Nation

The Nation

         

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In this file photo, heavy rain falls over the city of Bangkok at sunset during the monsoon season on September 18, 2011. Photo: AFP

September 2, 2025

BANGKOK – Bangkok will face thunderstorms with isolated heavy downpours, while the Andaman Sea and Gulf of Thailand are set to experience strong winds and high waves.

Over the next 24 hours, heavy rain is likely in the North, Northeast, Central region, and the Bangkok Metropolitan area. The East and the western South will see very heavy rainfall in some areas, especially in Lampang, Sukhothai, Kamphaeng Phet, Lamphun, Chiang Mai, Tak, Mae Hong Son, Udon Thani, Nong Bua Lamphu, Loei, Trat, Ranong, and Phang Nga.

Residents are urged to be on alert for flash floods and run-off, particularly in foothill zones, near waterways, and low-lying areas.

The warnings follow an active monsoon trough stretching across the North and Northeast, reinforced by a strong southwest monsoon covering the Andaman Sea and the Gulf.

In the upper Andaman Sea and upper Gulf of Thailand, waves are expected to reach 2–3 metres, rising above 3 metres in stormy areas. The lower Andaman Sea will see waves around 2 metres, higher during thundershowers.

Mariners are advised to proceed with caution and avoid sailing in stormy waters. Small boats in the upper Andaman and upper Gulf should remain ashore until September 2.

Thailand weather forecast: From 6am, Monday (September 1) to 6am, Tuesday (September 2)

Bangkok and vicinity

Thunderstorms are expected in 60% of the area, with heavy rain in some spots.

Minimum temperature: 25–27°C

Maximum temperature: 32–34°C

Southwesterly winds 10–20 km/h

North

Thunderstorms in 70% of the area, with heavy rain in places including Mae Hong Son, Chiang Mai, Lamphun, Lampang, Phrae, Uttaradit, Sukhothai, Tak, Kamphaeng Phet, Phitsanulok, Phichit, and Phetchabun.

Minimum temperature: 22–25°C

Maximum temperature: 27–33°C

Variable winds 10–20 km/h

Northeast

Thunderstorms in 70% of the area, with heavy rain in Loei, Udon Thani, Nong Bua Lamphu, Chaiyaphum, Khon Kaen, Maha Sarakham, Roi Et, Mukdahan, Yasothon, Amnat Charoen, and Ubon Ratchathani.

Minimum temperature: 22–25°C

Maximum temperature: 28–33°C

Variable winds 10–30 km/h

Central

Thunderstorms in 60% of the area, with heavy rain in Nakhon Sawan, Uthai Thani, Kanchanaburi, Nakhon Pathom, and Ratchaburi.

Minimum temperature: 23–26°C

Maximum temperature: 32–34°C

Southwesterly winds 10–20 km/h

East

Thunderstorms in 60% of the area, with heavy to very heavy rain in Nakhon Nayok, Prachin Buri, Chachoengsao, Rayong, Chanthaburi, and Trat.

Minimum temperature: 23–27°C

Maximum temperature: 28–34°C

Southwesterly winds 20–40 km/h

Waves 2–3 metres high, exceeding 3 metres in thundershowers

South (east coast)

Thunderstorms in 60% of the area, mainly in Phetchaburi, Prachuap Khiri Khan, Chumphon, and Surat Thani.

Minimum temperature: 23–25°C

Maximum temperature: 33–35°C

Southwesterly winds 20–35 km/h

Waves 1–2 metres, exceeding 2 metres offshore and in thundershowers

South (west coast)

Thunderstorms in 70% of the area, with heavy to very heavy rain in Ranong, Phang Nga, Phuket, and Krabi.

Minimum temperature: 23–26°C

Maximum temperature: 28–33°C

From Phuket northwards: Southwesterly winds 20–40 km/h; waves 2–3 metres, higher than 3 metres in thundershowers

From Krabi southwards: Southwesterly winds 20–35 km/h; waves around 2 metres, exceeding 2 metres in thundershowers

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