🗓️ September 18-20, 2026
📍 Thailand

🌧️ Thailand Heavy Rain Warning

The Thai Meteorological Department (TMD) is warning of heavy to very heavy rain in parts of Thailand from Friday, September 18 through Sunday, September 20, 2026.

⚠️ What You Need to Know

• Central Thailand and the South are expected to get the heaviest rain.
• Some areas could experience very heavy rain, especially in the southern provinces.
• Heavy rain could cause flash floods, flooding and fast-moving runoff.
• Low-lying areas, hillsides, slopes and areas near rivers and waterways are at greater risk.
• Take care when travelling and avoid roads that frequently flood.

🌊 Andaman Sea: Rough Seas

The Andaman Sea will have strong winds and rough waves.

• Waves will generally be 2–3 metres high.
• Waves can exceed 3 metres during thunderstorms.
• Small boats should stay onshore from September 18–20.
• Larger vessels should navigate carefully and avoid areas with thunderstorms.

📍 Bangkok & Surrounding Areas

• Thunderstorms are expected across about 80% of the area.
• Some areas may receive heavy rain.
• Temperatures: 24–26°C to 31–34°C.
• Winds: 10–25 km/h.

For Bangkok, expect frequent rain and thunderstorms, with a chance of locally heavy rain. Be particularly careful about temporary flooding and waterlogged roads.

📍 Central Thailand

About 80% of the region may see thunderstorms, with some areas receiving heavy rain.

Areas mentioned include Nakhon Sawan, Ayutthaya, Lopburi, Saraburi, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Sakhon and others.

🌴 Southern Thailand — West Coast

• About 80% of the area may have thunderstorms.
• Very heavy rain is possible in parts of Ranong, Phang Nga, Phuket and Krabi.
• Andaman Sea waves: 2–3 metres, potentially over 3 metres during thunderstorms.
• Small boats should remain ashore.

🌴 Southern Thailand — East Coast

About 60% of the area may have thunderstorms, with isolated heavy rain in places including Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung and Songkhla.

📍 Eastern Thailand

• About 70% of the area may experience thunderstorms.
• Some areas may receive heavy rain.
• Areas include Chonburi, Rayong, Chanthaburi and Trat.
• Waves could reach around 2 metres and higher during thunderstorms.

📍 Northern Thailand

About 70% of the region may experience thunderstorms, with some areas receiving heavy rain.

📍 Northeastern Thailand

About 60% of the region may experience thunderstorms, with some areas receiving heavy rain.

🗓️ Bottom Line

• 🌧️ Expect frequent rain and thunderstorms across much of Thailand.
• ⚠️ Central Thailand and especially parts of the South could see heavy or very heavy rain.
• 🌊 The Andaman Sea will be rough, with 2–3 metre waves.
• 🚤 Small boats on the Andaman Sea should stay ashore.
• 🚗 If you're travelling, watch for flooding and avoid roads that regularly flood.

The TMD recommends checking its latest updates before travelling, as conditions can change.