Southwest monsoon batters 40 Thai provinces with heavy rain and flash flood warnings across multiple regions; waves in the Andaman Sea and Gulf of Thailand reach 2–3 meters, with small boats advised to stay ashore until July 15.
The Meteorological Department warns that the southwest monsoon is battering 40 provinces nationwide with heavy rain, posing dangers of sudden flooding and flash floods across the Andaman Sea and Gulf of Thailand, with waves reaching 2–3 meters high.
For the next 24 hours, the northern, northeastern, and eastern regions are forecast to see heavy showers in some areas, with the east experiencing particularly severe rainfall in places. A low-pressure system sitting over northern Vietnam, combined with a moderately strong southwest monsoon blanketing the Andaman Sea, Thailand, and the Gulf of Thailand, is driving the weather pattern.
Residents are advised to beware of intense to very heavy rainfall and accumulated rain that could trigger flash floods and flash floods, especially in hillside areas near water channels and depression zones. In the upper Andaman Sea, winds and waves are moderately strong, with seas reaching 2–3 meters; thunderstorm areas may see waves exceeding 3 meters. The lower Andaman Sea and upper Gulf of Thailand will see waves around 2 meters, rising above 2 meters in thunderstorm zones. Fishermen must navigate cautiously and avoid thunderstorm areas; small boats in the upper Andaman Sea should remain ashore until July 15, 2026.
Detailed 24-hour weather forecast by region:
**Northern Region:** Thunderstorms 60% of area with heavy rain in places, especially around Mae Hong Son, Chiang Mai, Tak, Phitsanulok, and Phetchabun; lows 22–25°C, highs 32–35°C; southwest winds 10–20 km/h.
**Northeastern Region:** Thunderstorms 40% of area with heavy showers in Nong Khai, Bueng Kan, Sakon Nakhon, Nakhon Phanom, Udon Thani, Mukdahan, Amnat Charoen, and Ubon Ratchathani; lows 24–25°C, highs 33–36°C; southwest winds 10–20 km/h.
**Central Region:** Thunderstorms 60% of area, mainly around Nakhon Sawan, Uthai Thani, Chai Nat, Suphan Buri, Phra Nakhon Si Ayutthaya, Saraburi, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Songkhram, and Samut Sakhon; lows 23–25°C, highs 34–36°C; southwest winds 10–25 km/h.
**Eastern Region:** Thunderstorms 60% of area with heavy rain around Nakhon Nayok and Prachuap Khiri Khan; very heavy rainfall in Chanthaburi and Trat; lows 23–27°C, highs 31–35°C; southwest winds 20–35 km/h; coastal waves 2 meters, exceeding 2 meters in thunderstorm zones.
**Southern Region—Eastern Seaboard:** Thunderstorms 40% of area with heavy showers around Phetchaburi, Prachuap Khiri Khan, Chumphon, and Surat Thani; lows 23–26°C, highs 32–35°C. From Surat Thani northward: southwest winds 20–35 km/h; nearshore waves 1–2 meters, offshore 2 meters, exceeding 2 meters in thunderstorm areas. From Nakhon Si Thammarat southward: southwest winds 15–35 km/h; nearshore waves 1 meter, offshore 1–2 meters, exceeding 2 meters in thunderstorm zones.
**Southern Region—Western Seaboard:** Thunderstorms 60% of area with heavy showers around Ranong, Phang Nga, and Phuket; lows 23–26°C, highs 30–34°C; strong southwest winds in Phuket and northward.