A severe weather alert is in place as the Thai Meteorological Department (TMD) forecasts widespread heavy rain and thunderstorms across Thailand on Sunday, with Bangkok, its surrounding provinces, and the Northeast facing about a seventy-percent chance of storms.

The advisory covers the 24-hour period from 6 a.m. Sunday (28 September) to 6 a.m. Monday (29 September).

In the Northeast and the East, notably in provinces such as Sakon Nakhon, Nakhon Phanom, Udon Thani, Khon Kaen, Kalasin, Mukdahan, Chanthaburi, and Trat, heavy to very heavy rainfall is expected.

Residents in upper Thailand are urged to remain vigilant against flash floods, forest run-off, and river overflows—especially in low-lying zones, foothills, and areas adjacent to waterways.

Meteorologically, a robust monsoon trough extends across the lower North, upper Central, and lower Northeast regions of the country, while a strong southwesterly monsoon prevails over the Andaman Sea, the South, and the Gulf of Thailand.

Strong winds accompany these conditions, producing rough sea states: in the upper Andaman Sea, waves of two to three metres or more in stormy sectors; in the lower Andaman and upper Gulf, waves of about two metres, rising further in thunderstorm zones.

Mariners are cautioned to avoid navigation in hazardous seas.

Typhoon Bualoi, currently over the upper South China Sea, is projected to make landfall in northern Vietnam on 29 September.

As of 4 a.m. Sunday, its centre was located some 170 kilometres east of Da Nang, Vietnam, with maximum sustained winds near 120 km/h, tracking west-northwest at approximately 30 km/h.

The storm is expected to weaken gradually after landfall but will influence Thailand’s weather from 28–30 September, reinforcing heavy rain in the North, Northeast, East, and parts of the South.

Detailed regional forecasts anticipate:

• Bangkok and vicinity: thunderstorms in seventy percent of the area with isolated heavy rain; temperatures between twenty-four and twenty-six degrees Celsius at night, rising to thirty-one to thirty-three during the day; southwesterly winds at ten to twenty-five km/h.

• North: thunderstorms in forty percent of the area, focused in Tak, Kamphaeng Phet, Phitsanulok, Phichit, and Phetchabun; lows at twenty-two to twenty-four and highs at thirty-three to thirty-five; variable winds at ten to fifteen km/h.

• Northeast: storms in seventy percent of the area, with heavy to very heavy rainfall predicted in provinces including Nong Khai, Bueng Kan, Ubon Ratchathani, and others; nighttime lows of twenty-three to twenty-five and highs of thirty-one to thirty-four; winds varying between ten and thirty km/h.

• Central: storms in sixty percent, with isolated heavy rain in Kanchanaburi and Ratchaburi; lows of twenty-three to twenty-six, highs of thirty-three to thirty-four; southwesterly winds of ten to twenty-five km/h.

• East: thunderstorms in seventy percent of the area, heavy to very heavy rain in Nakhon Nayok, Prachin Buri, Rayong, Chanthaburi, and Trat; lows of twenty-three to twenty-six and highs of twenty-eight to thirty-three; winds of twenty to thirty-five km/h; waves around two metres, higher in storms.

• South (east coast): storms in seventy percent, isolated heavy rain in Prachuap Khiri Khan and Chumphon; lows twenty-three to twenty-five, highs thirty-one to thirty-four; southwest winds of fifteen to thirty-five km/h; waves reaching one to two metres and higher locally.

• South (west coast): storms in eighty percent, heavy to very heavy rain in Ranong, Phang Nga, Phuket, Krabi, Trang, and Satun; lows of twenty-four to twenty-six, highs of twenty-seven to thirty-two; winds from Phuket northwards at twenty to forty km/h with waves two to three metres or more; from Krabi southwards, waves around two metres and above in storms.

Authorities and local administrations are on alert.

Residents should heed flash flood warnings and avoid travel through vulnerable routes during peak rainfall.

Mariners are strongly discouraged from venturing into storm-affected seas.

Monitoring of river levels, particularly in flood-prone zones, has been heightened.

The TMD will continue to issue updates as the weather evolves and Typhoon Bualoi’s progression becomes clearer.