Heavy rain forecasted across Thailand with flash flood warnings

Heavy rain is forecasted across nearly all of Thailand, with 42 provinces, including Bangkok and its surrounding areas, expected to face severe weather. The Thai Meteorological Department (TMD) warns of flash floods, overflowing waterways, and high sea waves over 3 metres.

TMD issued a 24-hour weather forecast, starting from 5am today, September 4, predicting heavy rainfall in the lower northern region, northeastern region, central region including Bangkok and its vicinity, and the western coast of the southern region. The eastern region is expected to experience very heavy rain in some areas.

Citizens in these regions are advised to stay alert for potential dangers from heavy to very heavy rainfall, which could lead to flash floods and overflowing streams, especially in foothill areas near waterways and low-lying areas. Strong winds are also a concern.

The current weather conditions are influenced by a moderate monsoon trough passing through the lower northern, central, and lower northeastern regions, combined with a relatively strong southwest monsoon covering the Andaman Sea, the southern region, and the Gulf of Thailand. Additionally, a low-pressure system is covering the central region.

Sea conditions in the Andaman Sea and the upper Gulf of Thailand are expected to be relatively strong, with waves reaching 2 to 3 metres and over 3 metres in thunderstorm areas. In the lower Gulf of Thailand, waves are expected to be 1 to 2 metres high and over 2 meters in thunderstorm areas. Mariners in these regions are advised to navigate with caution and avoid sailing in thunderstorm areas, while small boats in the Andaman Sea and the upper Gulf of Thailand should stay ashore until at least September 8.

Meanwhile, the tropical storm Yagi over the upper South China Sea is expected to intensify into a typhoon. Between September 6 and 7, it is forecasted to pass over Hainan Island, China, and make landfall in northern Vietnam before gradually weakening. This weather pattern will bring heavy rain to some areas in the upper northern and northeastern regions of Thailand between September 7 and 8.

Heavy rainfall

Northern region: Thunderstorms are expected in 60% of the area, with heavy rain in some places, particularly in Tak, Kamphaeng Phet, Phichit, and Phetchabun provinces. The minimum temperature will be 23 to 26°C, and the maximum temperature will be 32 to 35°C.

Northeastern region: Thunderstorms are expected in 60% of the area, with heavy rain in some places, particularly in Nakhon Ratchasima, Buriram, Surin, Sisaket, and Ubon Ratchathani provinces. The minimum temperature will be 23 to 26°C, and the maximum temperature will be 32 to 34°C.

Central region: Thunderstorms are expected in 70% of the area, with heavy rain in some places, particularly in Nakhon Sawan, Uthai Thani, Chainat, Sing Buri, Ang Thong, Lop Buri, Saraburi, Phra Nakhon Si Ayutthaya, and Kanchanaburi provinces. The minimum temperature will be 23 to 26°C, and the maximum temperature will be 33 to 35°C.

Eastern region: Thunderstorms are expected in 70% of the area, with very heavy rain in some places, particularly in Nakhon Nayok, Prachin Buri, Chachoengsao, Chanthaburi, and Trat provinces. The minimum temperature will be 23 to 26°C, and the maximum temperature will be 28 to 33°C. Sea waves will be 2 to 3 metres high and over 3 metres in thunderstorm areas.

Southern region (east coast): Thunderstorms are expected in 60% of the area, mainly in Phetchaburi, Prachuap Khiri Khan, Chumphon, and Surat Thani provinces. The minimum temperature will be 23 to 25°C, and the maximum temperature will be 30 to 35°C. From Surat Thani upwards, sea waves will be around 2 metres high and over 2 metres in thunderstorm areas. From Nakhon Si Thammarat downwards, sea waves will be 1 to 2 metres high and over 2 metres in thunderstorm areas.

Southern region (west coast): Thunderstorms are expected in 60% of the area, with heavy rain in some places, particularly in Ranong, Phang Nga, and Phuket provinces. The minimum temperature will be 23 to 26°C, and the maximum temperature will be 29 to 34°C. Sea waves will be 2 to 3 metres high and over 3 metres in thunderstorm areas, reported KhaoSod.

Bangkok and vicinity: Thunderstorms are expected in 70% of the area, with heavy rain in some places. The minimum temperature will be 25 to 27°C, and the maximum temperature will be 31 to 34°C.