Thailand braces for monsoon rains, heavy downpours in Bangkok and east

The Meteorological Department has warned of widespread heavy rain across Thailand on Sunday (August 17), as a monsoon trough extends across the lower North and Northeast into a strong low-pressure system over the upper South China Sea.

Combined with a relatively strong south-westerly monsoon prevailing over the Andaman Sea, Thailand and the Gulf of Thailand, conditions are expected to bring significant rainfall.

Bangkok and its vicinity face a 70% chance of rain, while the eastern region is forecast to experience the heaviest downpours with an 80% chance of rainfall.

The public has been advised to remain vigilant, particularly in Mae Hong Son, Tak, Phitsanulok, Phetchabun, Chanthaburi, and Trat provinces, where torrential rain may cause flash floods and runoffs, especially in foothill areas, near waterways, and in low-lying zones.

At sea, waves in the upper Andaman Sea are expected to reach 2-3 metres, rising above 3 metres during thunderstorms.

In the lower Andaman Sea and the upper Gulf of Thailand, waves will be about 2 metres high, and over 2 metres during storms. Mariners are urged to proceed with caution, avoid sailing in stormy areas, and small boats in the upper Andaman Sea are advised to stay ashore until at least on Sunday.

The Meteorological Department has issued its 24-hour forecast for Thailand from 6am on Sunday (August 17) to 6am on Monday (August 18)

Bangkok and vicinity will see thunderstorms in 70% of areas, with some heavy rain. Temperatures will range between 25–27°C at night and 31–32°C during the day.

Northern region: Thunderstorms are expected in 70% of areas, with heavy rain in Mae Hong Son, Chiang Mai, Lamphun, Lampang, Phrae, Uttaradit, Sukhothai, Tak, Kamphaeng Phet, Phitsanulok, Phichit, and Phetchabun. Minimum temperatures 22–25°C, maximum 31–34°C.

Northeast: Thunderstorms in 70% of areas, with heavy rain in Chaiyaphum, Bueng Kan, Sakon Nakhon, Nakhon Phanom, Mukdahan, Amnat Charoen, Nakhon Ratchasima, and Ubon Ratchathani. Lows 23–24°C, highs 31–33°C.

Central region: Thunderstorms in 70% of areas, with heavy rain in Nakhon Sawan, Uthai Thani, Chai Nat, Lopburi, Saraburi, and Kanchanaburi. Temperatures 23–25°C at night, 32–33°C during the day.

Eastern region: Heavy to very heavy rain in 80% of areas, particularly in Nakhon Nayok, Prachin Buri, Sa Kaeo, Chachoengsao, Chon Buri, Rayong, Chanthaburi, and Trat. Minimum temperatures 23–26°C, maximum 28–33°C. Waves in the Gulf and eastern seas will reach around 2 metres, rising higher in thunderstorms.

Southern region (east coast): Thunderstorms in 60% of areas, with heavy rain in Prachuap Khiri Khan and Chumphon. Seas will see waves of 1–2 metres, higher offshore and during storms.

Southern region (west coast): Thunderstorms in 60% of areas, with heavy rain in Ranong and Phang Nga. Seas off Phuket and northwards will have waves of 2–3 metres, rising above 3 metres in storms. Southwards from Krabi, waves will reach about 2 metres.