Thunderstorms nationwide, 40 areas at risk of heavy rain and floods

The Meteorological Department forecasts thunderstorms nationwide over the next 24 hours, with heavy rain expected in parts of the Northeast, Central region (including Bangkok and surrounding provinces), the East, and the South. 

Residents in these areas are advised to remain alert to potential flash floods and run-off from accumulated rainfall.

The unsettled weather is being driven by the monsoon trough lying across the lower North, Central, East, and lower Northeast, combined with a moderate southwesterly monsoon prevailing over the Andaman Sea, the South, and the Gulf of Thailand.

Marine conditions:

Upper Andaman Sea: moderate waves 1–2 metres, higher than 2 metres in stormy areas.

Lower Andaman Sea & Gulf of Thailand: waves around 1 metre, rising above 2 metres in thunderstorms. Mariners should exercise caution and avoid sailing in stormy areas.

Regional forecasts From 6pm on Friday(September 12) to 6pm on Saturday(September 13)

North

• Thunderstorms over 60% of the area, especially Mae Hong Son, Chiang Mai, Chiang Rai, Lamphun, Lampang, Tak, Phitsanulok, Phichit and Phetchabun.
• Temperature: 22–25°C (low), 32–35°C (high).
• Winds: variable, 5–15 km/h.

Northeast

• Thunderstorms in 60% of the area with heavy rain in Roi Et, Yasothon, Amnat Charoen, Nakhon Ratchasima, Buri Ram, Surin, Si Sa Ket, and Ubon Ratchathani.
• Temperature: 23–25°C (low), 33–35°C (high).
• Winds: variable, 10–15 km/h.

Central

• Thunderstorms in 70% of the area, heavy rain in Nakhon Sawan, Uthai Thani, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Sakhon, and Samut Songkhram.
• Temperature: 23–25°C (low), 33–35°C (high).
• Winds: variable, 10–15 km/h.

Bangkok and surrounding areas

• Thunderstorms in 70% of the area, with heavy rain in some places.
• Temperature: 25–27°C (low), 32–34°C (high).
• Winds: southwesterly, 10–15 km/h.

East

• Thunderstorms in 70% of the area, heavy rain in Sa Kaeo, Chachoengsao, Chon Buri, Rayong, Chanthaburi, and Trat.
• Temperature: 23–26°C (low), 31–34°C (high).
• Winds: southwesterly, 15–30 km/h.
• Sea waves: around 1 metre, over 2 metres in thunderstorms.

South (east coast)

• Thunderstorms in 70% of the area, heavy rain in Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani, Yala, and Narathiwat.
• Temperature: 23–25°C (low), 32–34°C (high).
• Winds: southwesterly, 15–30 km/h.
• Sea waves: around 1 metre, over 2 metres in thunderstorms.

South (west coast)

• Thunderstorms in 60% of the area, heavy rain in Krabi, Trang, and Satun.
• Temperature: 23–25°C (low), 31–33°C (high).
• From Phuket northwards: southwesterly winds 15–35 km/h, waves 1–2 metres, above 2 metres in thunderstorms.
• From Krabi southwards: southwesterly winds 15–30 km/h, waves around 1 metre, above 2 metres in thunderstorms.

Thailand 7-day weather forecast (September 12–18, 2025)

September 12–16

Rainfall will ease in the upper North and upper Northeast. However, heavy showers will persist in some areas as the monsoon trough lies across the lower North, Central, East, and lower Northeast, reinforced by the southwesterly monsoon prevailing over the Andaman Sea, the South, and the Gulf of Thailand.Sea conditions: Waves in the upper Andaman Sea will be 1–2 metres, while the lower Andaman Sea and upper Gulf of Thailand will see waves around 1 metre, rising above 2 metres in thunderstorms.

September 17–18

Heavy to very heavy rain is forecast in parts of the lower North, lower Northeast, Central region (including Bangkok and surrounding provinces), and the South, with the most intense rainfall expected in the East and along the west coast of the South. This is due to the monsoon trough shifting southward across the Central, East, and lower Northeast regions, while the southwesterly monsoon over the Andaman Sea, Thailand, and the Gulf of Thailand strengthens.

Sea conditions: Moderate winds and waves, with the upper Andaman Sea seeing waves up to 2 metres. The lower Andaman and upper Gulf of Thailand will experience waves 1–2 metres, rising above 2 metres in stormy areas.

Advisory

From September 17–18, residents in the lower North, lower Northeast, Central region (including Bangkok and surrounding provinces), East, and South should beware of dangers from heavy to very heavy rainfall and accumulated rain, which may cause flash floods and run-off, especially in foothills, waterways, and low-lying areas. Mariners should proceed with caution and avoid sailing in storm-affected zones throughout the period.

Disaster Prevention Department urges vigilance as Chao Phraya River rises

At 12.20pm on Friday, the Department of Disaster Prevention and Mitigation (DDPM) instructed Uthai Thani and Chai Nat provinces, particularly communities along the Chao Phraya River upstream of the Chao Phraya Dam, to closely monitor rising water levels. 

Officials were ordered to step up 24-hour surveillance, especially in low-lying areas outside flood barriers, and to alert local agencies, riverside businesses, and residents to prepare for possible flooding.

The DDPM, acting as the Central Disaster Command Centre, reported information from the Royal Irrigation Department. On September 10, water discharge at Station C.2 in Nakhon Sawan district reached around 2,067 cubic metres per second, with the water level upstream of the Chao Phraya Dam at +16.69 m MSL and downstream at +14.37 m MSL. 

Water inflow to irrigation canals on both banks was 292 cubic metres per second, while outflow through the dam was 1,900 cubic metres per second.

However, stagnant flooding downstream has already affected riverside communities outside flood barriers. To ease the situation, authorities have temporarily held excess water upstream of the dam, raising water levels but not beyond +17.50 m MSL.

Areas at risk

Uthai Thani:

• Riverside areas of Hat Thanong, Ko Thepho, Sakang Rang, Nam Sum and Tha Sung subdistricts, Mueang Uthai Thani district.

Chai Nat:

• Riverside areas of Siladan, Chanun, Wat Khok and Khung Samphao subdistricts, Manorom district.
• Riverside areas of Wat Sing and Makham Thao subdistricts, Wat Sing district.
• Riverside and low-lying areas of Tha Chai, Hat Tha Sao, Thammamool, Khao Tha Phra and Chai Nat subdistricts, Mueang Chai Nat district.
• Makham Thao Canal areas: Chuan Wilai community, Tha Sala community, Makham Thao community, and adjacent riverside areas of Makham Thao subdistrict, Wat Sing district.

Public advisory

Residents are urged to follow official updates closely, strictly comply with safety guidance, and prepare for possible flooding, flash floods, or runoff.

Those affected may request assistance via the Line account “ปภ.รับแจ้งเหตุ 1784” (Line ID: @1784DDPM) or call the 1784 safety hotline available 24/7. Alerts are also available on the THAI DISASTER ALERT application.