Heavy rain and thunderstorms forecast for Monday, 70% chance in Bangkok and South

In the next 24 hours, the Northeast, Central region including Bangkok and its vicinity, the East, and the South will continue to see heavy downpours. The conditions are caused by a monsoon trough passing over the Central region, upper South, and East, into a low-pressure system along Vietnam’s lower coast, coupled with southeasterly winds covering the lower Northeast, the East, and the upper Gulf of Thailand.

The moderate southwesterly monsoon over the Andaman Sea, the South, and the Gulf of Thailand will bring further unsettled weather. The public is advised to beware of flash floods and runoff, particularly in foothill areas, near waterways, and low-lying zones.

Waves in the upper Andaman Sea are expected to reach 1–2 metres, while those in the lower Andaman and Gulf of Thailand will be about 1 metre. In stormy areas, waves may exceed 2 metres. Mariners are urged to proceed with caution and avoid sailing in thunderstorm zones.

Thailand weather forecast: September 15–16, 2025 (6am Monday to 6am Tuesday)

Bangkok and surrounding provinces

• Thunderstorms over 70% of the area with isolated heavy rain.
• Low: 25–26°C | High: 32–33°C | Variable winds 10–15 km/h.

North

• Thunderstorms in 40% of the area, mainly in Mae Hong Son, Lamphun, Lampang, Tak, Phitsanulok, Phichit and Phetchabun.
• Low: 22–25°C | High: 31–34°C | Variable winds 5–15 km/h.

Northeast

• Thunderstorms in 60% of the area with isolated heavy rain, especially in Chaiyaphum, Khon Kaen, Roi Et, Buri Ram, Nakhon Ratchasima and Surin.
• Low: 22–24°C | High: 30–34°C | Easterly winds 10–15 km/h.

Central

• Thunderstorms in 70% of the area with heavy rain in Lop Buri, Saraburi, Ayutthaya, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Sakhon and Samut Songkhram.
• Low: 25–26°C | High: 32–34°C | Variable winds 10–15 km/h.

East

• Thunderstorms in 70% of the area with heavy rain in Nakhon Nayok, Sa Kaeo, Chachoengsao, Chonburi, Rayong, Chanthaburi and Trat.
• Low: 24–25°C | High: 29–33°C | Variable winds 15–30 km/h.
• Sea waves about 1m, rising above 2m in thundershowers.

South (east coast)

• Thunderstorms in 70% of the area with heavy to very heavy rain in Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Nakhon Si Thammarat, Pattani, Yala and Narathiwat.
• Low: 23–25°C | High: 31–34°C | Southwesterly winds 15–30 km/h.
• Sea waves about 1m, above 2m in thundershowers.

South (west coast)

• Thunderstorms in 70% of the area with heavy rain in Phang Nga, Krabi, Trang and Satun.
• Low: 23–24°C | High: 30–33°C.
• From Phuket northwards: southwesterly winds 15–35 km/h, waves 1–2m, above 2m in thundershowers.
• From Krabi southwards: southwesterly winds 15–30 km/h, waves about 1m, above 2m in thundershowers.