Heavy rainfall is expected across Thailand's northern and northeastern regions through July 18 due to the southwest monsoon, with residents warned of potential flooding and flash floods in foothill and low-lying areas.
On July 17, 2025, the Meteorological Department issued a 24-hour weather forecast predicting scattered thunderstorms across Thailand, with heavy rainfall persisting in the northern and northeastern regions due to the southwest monsoon affecting the Andaman Sea, Thailand, and the Gulf of Thailand. A low-pressure system is also centered over northern Vietnam.
Residents in the North and Northeast should be alert to dangers from heavy and accumulated rainfall, which may cause sudden flooding and flash floods, particularly in foothill areas near water channels and in low-lying zones.
For the Andaman Sea's upper section and upper Gulf of Thailand, waves will reach 1-2 meters high. The lower Andaman Sea will see waves around 1 meter, with thunderstorm areas experiencing waves exceeding 2 meters. Fishermen are advised to navigate cautiously and avoid thunderstorm zones.
**Northern Region:**
40% chance of thunderstorms with heavy rain in some areas, particularly in Chiang Rai, Phayao, Lampang, Nan, Phrae, and Uttaradit provinces. Minimum temperature 22-25°C, maximum 31-33°C. Southwest winds 10-20 km/h.
**Northeastern Region:**
30% chance of thunderstorms, mainly around Nong Khai, Bueng Kan, Sakon Nakhon, Nakhon Phanom, Mukdahan, Amnat Charoen, and Ubon Ratchathani. Minimum temperature 23-26°C, maximum 32-36°C. Southwest winds 10-20 km/h.
**Central Region:**
30% chance of thunderstorms, mainly in Lopburi, Saraburi, Uthai Thani, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Songkhram, and Samut Sakhon. Minimum temperature 24-26°C, maximum 34-36°C. Southwest winds 10-20 km/h.
**Eastern Region:**
40% chance of thunderstorms with heavy rain in some areas, particularly in Chanthaburi and Trat. Minimum temperature 23-27°C, maximum 31-34°C. Southwest winds 15-35 km/h. Waves 1-2 meters; exceed 2 meters in thunderstorm areas.
**Southern Region (East Coast):**
30% chance of thunderstorms, mainly in Phetchaburi, Prachuap Khiri Khan, Chumphon, Pattani, Yala, and Narathiwat. Minimum temperature 23-25°C, maximum 33-36°C. Southwest winds 15-30 km/h. Waves approximately 1 meter offshore, exceeding 1 meter further out and 2 meters in thunderstorm areas.
**Southern Region (West Coast):**
30% chance of thunderstorms, mainly in Ranong, Phang Nga, Trang, and Satun. Minimum temperature 24-25°C, maximum 32-35°C. From Phang Nga northward: southwest winds 15-35 km/h, waves 1-2 meters, exceeding 2 meters in thunderstorm areas. From Phuket southward: southwest winds 15-30 km/h, waves approximately 1 meter, exceeding 2 meters in thunderstorm areas.
**Bangkok and Vicinity:**
40% chance of thunderstorms. Minimum temperature 24-26°C, maximum 34-35°C. Southwest winds 10-20 km/h.