Four Thai regions face heavy rain as southwest monsoon strengthens
Thunderstorms are expected over 70% of the North and Northeast, with flash-flood risks and waves exceeding three metres in the upper Andaman Sea during storms.
- Heavy rain is forecast for four regions in Thailand: the North, Northeast, East, and the South’s west coast.
- The severe weather is attributed to a strengthening southwest monsoon over the Andaman Sea, Thailand, and the Gulf of Thailand.
- Authorities have warned the public about the risk of flash floods and forest run-off due to heavy and accumulated rainfall.
- A maritime warning has been issued for strong winds and high waves (2-3 meters or more), advising small boats in the upper Andaman Sea to stay ashore.
The Thai Meteorological Department (TMD) forecast thunderstorms across 70% of the North and Northeast, with isolated heavy rain, on Monday (July 27, 2026).
Bangkok and surrounding provinces were expected to see scattered thunderstorms.
Over the next 24 hours, isolated heavy rain was expected in the North, Northeast, East and on the South’s west coast.
A monsoon trough lay across the upper North and upper Laos, while the moderate southwest monsoon prevailing over the Andaman Sea, Thailand and the Gulf of Thailand was strengthening.
People were advised to beware of heavy rain and accumulated rainfall, which could cause flash floods and forest run-off, particularly in foothill areas near waterways and in low-lying areas.
Winds and waves in the upper Andaman Sea were rather strong, with waves of 2–3 metres and more than 3 metres during thunderstorms.
Waves in the lower Andaman Sea and the upper Gulf of Thailand were around 2 metres, rising above 2 metres during thunderstorms.
Mariners were advised to proceed with caution and avoid storm areas, while small boats in the upper Andaman Sea should remain ashore.
Weather forecast for Thailand from 6am on Monday (July 27) to 6am on Tuesday (July 28)
Bangkok and surrounding provinces
- Thunderstorms are forecast across 40% of the area.
- Minimum temperatures: 26–28°C
- Maximum temperatures: 34–36°C
- Southwesterly winds: 10–25 km/h
North
- Thunderstorms are forecast across 70% of the area, with isolated heavy rain in Mae Hong Son, Chiang Rai, Tak, Nan, Phitsanulok and Phetchabun.
- Minimum temperatures: 22–27°C
- Maximum temperatures: 30–36°C
- Southwesterly winds: 10–20 km/h
Northeast
- Thunderstorms are forecast across 70% of the area, with isolated heavy rain in Nong Khai, Bueng Kan, Udon Thani, Sakon Nakhon, Nakhon Phanom, Mukdahan, Yasothon, Amnat Charoen, Si Sa Ket and Ubon Ratchathani.
- Minimum temperatures: 23–25°C
- Maximum temperatures: 31–35°C
- Southwesterly winds: 10–20 km/h
Central region
- Thunderstorms are forecast across 40% of the area, mainly in Uthai Thani, Chai Nat, Phra Nakhon Si Ayutthaya, Kanchanaburi and Ratchaburi.
- Minimum temperatures: 24–26°C
- Maximum temperatures: 34–37°C
- Southwesterly winds: 10–25 km/h
East
- Thunderstorms are forecast across 70% of the area, with isolated heavy rain in Chanthaburi and Trat.
- Minimum temperatures: 23–27°C
- Maximum temperatures: 30–35°C
- Southwesterly winds: 20–35 km/h
- Waves will be around 2 metres, rising above 2 metres during thunderstorms.
Southern region, east coast
- Thunderstorms are forecast across 40% of the area, mainly in Phetchaburi, Prachuap Khiri Khan, Chumphon and Surat Thani.
- Minimum temperatures: 23–26°C
- Maximum temperatures: 32–35°C
- Southwesterly winds: 15–35 km/h
- Waves will be around 1 metre, reaching 1–2 metres offshore and more than 2 metres during thunderstorms.
Southern region, west coast
- Thunderstorms are forecast across 60% of the area, with isolated heavy rain in Ranong and Phang Nga.
- Minimum temperatures: 22–26°C
- Maximum temperatures: 29–34°C
- From Phang Nga northwards, southwesterly winds will reach 20–40 km/h. Waves will be 2–3 metres, rising above 3 metres during thunderstorms.
- From Phuket southwards, southwesterly winds will reach 20–35 km/h. Waves will be around 2 metres, rising above 2 metres during thunderstorms.
