Nine northern provinces face heavy rain and flood risk

Heavy rain is forecast across northern, northeastern, central and eastern Thailand on Wednesday (August 12), with authorities warning of flash floods and forest run-off after a monsoon trough moved across the upper North.

The Thai Meteorological Department said the trough extends across upper northern Thailand, upper Laos and the upper Northeast, while a fairly strong southwest monsoon is prevailing over the Andaman Sea, Thailand and the Gulf of Thailand.

People in affected areas have been advised to watch for heavy and accumulated rainfall, particularly in foothill areas near waterways and in low-lying locations where flash floods and forest run-off could occur.

The upper Andaman Sea and upper Gulf of Thailand will see fairly strong conditions, with waves of 2-3 metres and heights exceeding three metres in thunderstorms.

Mariners have been advised to proceed with caution and avoid areas affected by thunderstorms, while small boats in the upper Andaman Sea and upper Gulf should remain ashore.

Regional forecasts for August 12

North: Thunderstorms across 70% of the region, with heavy rain in Mae Hong Son, Chiang Mai, Chiang Rai, Lampang, Phayao, Nan, Uttaradit, Tak and Phetchabun. Temperatures are forecast at 22-27C overnight and 30-34C during the day, with southwesterly winds of 10-20 kilometres per hour.

Northeast: Thunderstorms across 60% of the region, with heavy rain in Loei, Nong Khai, Bueng Kan, Udon Thani, Sakon Nakhon, Nakhon Phanom, Mukdahan, Amnat Charoen and Ubon Ratchathani. Temperatures will range from 23-25C to 30-34C, with southwesterly winds of 10-20kph.

Central region: Thunderstorms across 60% of the area, with heavy rain in Uthai Thani, Kanchanaburi and Ratchaburi. Temperatures will range from 24-26C to 32-34C, with southwesterly winds of 10-25kph.

East: Thunderstorms across 60% of the region, with heavy rain in Nakhon Nayok, Prachin Buri, Chanthaburi and Trat. Temperatures will range from 24-27C to 30-34C, with southwesterly winds of 20-40kph. Waves are forecast at 2-3 metres and above three metres during thunderstorms.

Southern east coast: Thunderstorms across 40% of the region, mainly in Phetchaburi, Prachuap Khiri Khan, Chumphon, Songkhla, Pattani, Yala and Narathiwat. Temperatures will range from 23-25C to 32-36C. Waves will be 1-2 metres, rising above two metres offshore and during thunderstorms.

Southern west coast: Thunderstorms across 40% of the region, mainly in Ranong, Krabi, Trang and Satun. Temperatures will range from 24-28C to 31-35C. From Phang Nga northwards, waves will reach 2-3 metres and exceed three metres during thunderstorms. From Phuket southwards, waves will be about two metres and above two metres during thunderstorms.

Bangkok and surrounding provinces: Thunderstorms are forecast across 60% of the area. Temperatures will range from 26-27C to 32-34C, with southwesterly winds of 10-25kph.