TMD forecasts rain across 70% of Bangkok area on Sept 28

The Thai Meteorological Department (TMD) forecasts less rain in Bangkok and surrounding provinces on September 28, 2026, although thunderstorms are still expected across 70% of the area, with isolated heavy downpours. The forecast covers the 24 hours from 6am on September 28 to 6am on September 29, Thailand time. The TMD said the low-pressure system had moved into the Gulf of Martaban, while a relatively strong south-west monsoon continued to cover the Andaman Sea, southern Thailand and the Gulf of Thailand.

Heavy rain threatens the North, Central region and East

The TMD forecasts isolated heavy to very heavy rain in western and lower parts of the North, western parts of the Central region and the East. Rainfall elsewhere is expected to decrease, although heavy showers remain possible in some areas.

The TMD warned residents, particularly in the North, Central region and East, that heavy and accumulated rainfall could cause flash floods, further flooding, overflowing rivers, rapid run-off and landslides. Particular risks remain near waterways at the foot of hills and in low-lying areas.

The TMD advised travellers to avoid routes prone to repeated flooding, especially low-lying roads where temporary waterlogging could occur.
TMD advises small boats to stay ashore through September 28

Small boats in the upper Andaman Sea and upper Gulf of Thailand should remain ashore through September 28, the TMD advised. Waves in both areas are expected to reach 2–3 metres and exceed three metres during thunderstorms.

The TMD urged vessels elsewhere in the Andaman Sea and Gulf of Thailand to proceed cautiously and avoid thunderstorms. The small-boat advisory continues the warning to remain ashore through September 28 covered in the department’s earlier forecast. 

TMD regional forecasts retain heavy-rain warnings

The TMD’s regional forecast retains the possibility of heavy rain across all forecast areas from 6am on September 28 to 6am on September 29. Rain percentages refer to the proportion of each area expected to receive thunderstorms.

Bangkok and surrounding provinces: Thunderstorms across 70% of the area, with isolated heavy rain. Minimum temperatures of 23–24°C and maximum temperatures of 29–31°C. Southerly winds at 10–25 km/h.

North: Thunderstorms across 60% of the region, with isolated heavy rain in Chiang Rai, Lamphun, Lampang, Phrae, Sukhothai and Phetchabun. Isolated very heavy rain is forecast in Mae Hong Son, Chiang Mai and Tak. Minimum temperatures of 23–25°C and maximum temperatures of 30–34°C. Easterly winds at 10–20 km/h.

Northeast: Thunderstorms across 60% of the region, with isolated heavy rain in Chaiyaphum, Nakhon Ratchasima and Buri Ram. Minimum temperatures of 23–24°C and maximum temperatures of 30–33°C. Easterly winds at 10–25 km/h.

Central region: Thunderstorms across 70% of the region, with isolated heavy rain in Chai Nat, Lop Buri, Saraburi, Sing Buri, Ang Thong, Phra Nakhon Si Ayutthaya, Nakhon Pathom, Samut Sakhon and Samut Songkhram. Isolated very heavy rain is forecast in Nakhon Sawan, Uthai Thani, Suphan Buri, Kanchanaburi and Ratchaburi. Minimum temperatures of 22–24°C and maximum temperatures of 28–31°C. Variable winds at 10–25 km/h.

East: Thunderstorms across 70% of the region, with isolated heavy rain in Prachin Buri, Sa Kaeo and Chachoengsao. Isolated very heavy rain is forecast in Nakhon Nayok, Chonburi, Rayong, Chanthaburi and Trat. Minimum temperatures of 23–24°C and maximum temperatures of 28–32°C. South-westerly winds at 20–40 km/h, with waves of 2–3 metres, exceeding three metres in thunderstorms.

South’s east coast: Thunderstorms across 60% of the area, with isolated heavy rain in Phetchaburi and Prachuap Khiri Khan. Minimum temperatures of 21–24°C and maximum temperatures of 30–34°C. From Surat Thani northwards, south-westerly winds at 20–35 km/h, with waves of about two metres, exceeding three metres in thunderstorms. From Nakhon Si Thammarat southwards, south-westerly winds at 15–35 km/h, with waves of 1–2 metres, exceeding three metres in thunderstorms.

South’s west coast: Thunderstorms across 60% of the area, with isolated heavy rain in Ranong, Phang Nga and Phuket. Minimum temperatures of 23–25°C and maximum temperatures of 30–34°C. From Ranong northwards, south-westerly winds at 20–40 km/h, with waves of 2–3 metres, exceeding three metres in thunderstorms. From Phang Nga southwards, south-westerly winds at 15–35 km/h, with waves of 1–2 metres, exceeding two metres in thunderstorms.