Thailand is bracing for widespread heavy rain and the risk of flash floods over the next 24 hours, the Thai Meteorological Department (TMD) said, with the heaviest downpours expected in the North, Northeast and East. A monsoon trough lying across the upper North and upper Northeast is feeding into a low-pressure area over the Gulf of Tonkin, while a strong southwest monsoon is sweeping across the Andaman Sea, mainland Thailand and the Gulf of Thailand.
TMD’s forecast covers the 24-hour period from 6am on 8 August 2026 to 6am on 9 August 2026.
Residents in the affected areas have been urged to watch for danger from heavy to very heavy rain and accumulated rainfall, which could trigger flash floods and forest run-off, particularly on sloping ground near waterways and in low-lying areas.
North
Thunderstorms are forecast to cover 80% of the region, with heavy rain in several areas, including Mae Hong Son, Chiang Mai, Lampang, Phrae, Sukhothai, Tak, Kamphaeng Phet and Phichit. Very heavy rain is possible in parts of Chiang Rai, Phayao, Nan, Uttaradit, Phitsanulok and Phetchabun. Temperatures will range from a low of 22 to 26°C to a high of 31 to 36°C, with southwesterly winds of 10 to 20 kilometres per hour.
Northeast
Thunderstorms are expected across 70% of the region, with heavy rain in parts of Nong Bua Lamphu, Kalasin, Mukdahan, Yasothon, Amnat Charoen and Ubon Ratchathani. Very heavy rain is possible in areas of Loei, Nong Khai, Bueng Kan, Udon Thani, Sakon Nakhon and Nakhon Phanom. Temperatures will range from 22 to 25°C at the low end to 27 to 34°C at the high end, with southwesterly winds of 10 to 20 kilometres per hour.
Central
Thunderstorms are forecast over 60% of the region, with heavy rain in parts of Nakhon Sawan, Uthai Thani, Lop Buri, Saraburi, Kanchanaburi and Ratchaburi. Temperatures will range from 24 to 26°C to 33 to 35°C, with southwesterly winds of 10 to 25 kilometres per hour.
East
Thunderstorms are expected across 70% of the region, with heavy rain in parts of Nakhon Nayok, Prachin Buri and Rayong, and very heavy rain possible in Chanthaburi and Trat. Temperatures will range from 23 to 28°C to 30 to 34°C, with southwesterly winds of 20 to 40 kilometres per hour. Seas will run 2 to 3 metres, rising above 3 metres in thundery conditions.
South East Coast
Thunderstorms are forecast over 40% of the region, mostly in Phetchaburi, Prachuap Khiri Khan, Chumphon and Surat Thani. Temperatures will range from 23 to 26°C to 32 to 36°C, with southwesterly winds of 20 to 35 kilometres per hour. Seas will run 1 to 2 metres, rising above 2 metres further offshore and in thundery areas.
South West Coast
Thunderstorms are expected over 60% of the region, with heavy rain in parts of Ranong and Phang Nga. Temperatures will range from 23 to 27°C to 31 to 35°C. From Phuket northwards, southwesterly winds of 20 to 40 kilometres per hour will bring seas of 2 to 3 metres, rising above 3 metres in thundery conditions. From Krabi southwards, southwesterly winds of 20 to 35 kilometres per hour will bring seas of around 2 metres, rising above 2 metres in thundery conditions.
Bangkok and Vicinity
Thunderstorms are forecast across 70% of the capital and surrounding provinces, with heavy rain in some areas. Temperatures will range from 25 to 28°C to 32 to 35°C, with southwesterly winds of 10 to 25 kilometres per hour.
Sea Conditions
Seas in the upper Andaman Sea and upper Gulf of Thailand will be rough, with waves of 2 to 3 metres and above 3 metres in thundery areas. Mariners have been advised to navigate with caution and avoid thunderstorm areas, while small boats in the upper Andaman Sea and upper Gulf have been told to stay ashore.
Typhoon Dolphin
Separately, TMD noted that Typhoon Dolphin is moving through the Pacific Ocean west of Okinawa, Japan, and is expected to make landfall in China’s Zhejiang province between 9 and 10 August 2026. The typhoon is not forecast to track into Thailand, though anyone travelling to the affected region has been advised to check conditions before departure.
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