Meteorological Department Issues Bulletin No.1: Heavy to Very Heavy Rainfall Forecast, Check Flood Risk Areas 18-25 Oct 2026

The Meteorological Department issued Bulletin No. 1 warning of heavy to very heavy rainfall across Thailand, highlighting provinces at risk of flash floods, mountain runoff floods, and waterlogging, with impacts expected between 18-25 October 2026.

At 05:00 on 17 October 2026 GMT+7.Meteorological Department.Bulletin No. 1 regarding heavy to very heavy rainfall over Thailand (effective 18-25 October 2026).

On 18 October 2026, heavy rain expected in many southern provinces.

Heavy rain (35.1–65 mm). Beware of waterlogging in low-lying and poorly drained areas, especially where rainfall has accumulated.

Forecast for Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Pattani, Yala, Narathiwat, Ranong, Phang Nga, Phuket, Krabi, Trang, and Satun provinces.

On 19 October 2026, southern region continues to experience heavy rain.

Heavy rain (35.1–65 mm). Beware of waterlogging in low-lying or poorly drained areas, especially where rainfall has accumulated.

Forecast for Chumphon, Surat Thani, Nakhon Si Thammarat, Phatthalung, Songkhla, Yala, Narathiwat, Ranong, Phang Nga, Phuket, Krabi, Trang, and Satun provinces.

On 20 October 2026, heavy rain expected in eastern and upper southern regions.

Heavy rain (35.1–65 mm). Beware of waterlogging in low-lying or poorly drained areas, especially where rainfall has accumulated.

Eastern region: Chonburi, Rayong, Chanthaburi, Trat.

Southern region: Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Ranong, Phang Nga.

On 21 October 2026, rain increases in many areas with very heavy rain in some locations.

Very heavy rain (65.1–125 mm). Flash floods and mountain runoff may occur in risk areas, especially where heavy or continuous rainfall occurs.

Eastern region: Chonburi, Rayong, Chanthaburi.

Southern region: Phetchaburi.

Heavy rain (35.1–65 mm). Beware of waterlogging in low-lying and poorly drained areas, especially where rainfall has accumulated.

Lower northeastern region: Nakhon Ratchasima, Buriram, Ubon Ratchathani.

Central region: Suphanburi, Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Sakhon, Samut Songkhram, Bangkok and vicinity.

Eastern region: Nakhon Nayok, Prachinburi, Chachoengsao, Trat.

Southern region: Prachuap Khiri Khan.

On 22 October 2026, eastern region still expects very heavy rain.

Very heavy rain (65.1–125 mm). Flash floods and mountain runoff may occur in risk areas, especially where heavy or continuous rainfall occurs.

Heavy rain (35.1–65 mm). Beware of waterlogging in low-lying and poorly drained areas, especially where rainfall has accumulated.

Central region: Samut Songkhram, Bangkok and vicinity.

Eastern region: Chachoengsao, Chanthaburi, Trat.

Southern region: Phetchaburi.

On 23 October 2026, heavy rain scattered over many areas.

Heavy rain (35.1–65 mm). Beware of waterlogging in low-lying and poorly drained areas, especially where rainfall has accumulated.

Central region: Kanchanaburi, Ratchaburi, Nakhon Pathom, Samut Sakhon, Samut Songkhram, Bangkok and vicinity.

Eastern region: Chachoengsao, Chonburi, Rayong.

Southern region: Phetchaburi, Prachuap Khiri Khan, Chumphon, Ranong, Phang Nga, Phuket.

On 24 October 2026, very heavy rain mainly on the Andaman side of the south.

Very heavy rain (65.1–125 mm). Flash floods and mountain runoff may occur in risk areas, especially where heavy or continuous rainfall occurs. Forecast for Phang Nga, Phuket, Krabi provinces.

Heavy rain (35.1–65 mm). Beware of waterlogging in low-lying and poorly drained areas, especially where rainfall has accumulated.

Central region: Samut Sakhon, Bangkok and vicinity.

Eastern region: Chonburi, Rayong.

Southern region: Phetchaburi, Prachuap Khiri Khan, Chumphon, Surat Thani, Nakhon Si Thammarat, Ranong, Trang.

On 25 October 2026, southern region still needs to watch for very heavy rain.

Very heavy rain (65.1–125 mm). Flash floods and mountain runoff may occur in risk areas, especially where heavy or continuous rainfall occurs. Forecast for Phetchaburi, Prachuap Khiri Khan, Ranong, Phang Nga, Phuket provinces.

Heavy rain (35.1–65 mm). Beware of waterlogging in low-lying and poorly drained areas, especially where rainfall has accumulated.

Central region: Ratchaburi, Samut Sakhon, Samut Songkhram.

Southern region: Surat Thani, Songkhla, Krabi.

Bangkok and vicinity.

Forecast indicates heavy rain in some areas from 21–24 October 2026.

Heavy rain (35.1–65 mm). Beware of waterlogging in low-lying and poorly drained areas, especially where rainfall has accumulated.

This is a forecast indicating possible areas; heavy rain will not occur everywhere. Following local updates will help prepare more effectively.

Meteorological Department: Check daily forecasts, warnings, and rain radar.

Royal Irrigation Department / National Water Resources Office: Monitor water levels and water situations.

Department of Disaster Prevention and Mitigation / Provincial / Local agencies: Issue warnings for risk areas and affected routes.

Information per Meteorological Department Bulletin No. 1 (260/2569). Please follow the latest updates as forecasts may change.