ONWR issues tidal flood alert for Bangkok and six nearby provinces
Combination of seasonal high tides and a strengthening northeast monsoon could push seawater inland, lifting water levels in key rivers and raising risk of flooding in low-lying riverside communities outside embankments between January 2–9, 2026.
- The Office of the National Water Resources (ONWR) has issued a tidal flood alert for the period of January 2-9.
- The warning applies to Bangkok and six other provinces: Samut Prakan, Nonthaburi, Pathum Thani, Samut Sakhon, Nakhon Pathom, and Samut Songkhram.
- The flood risk is caused by a combination of seasonal high tides and a strengthening northeast monsoon, which could push seawater inland.
- Residents in low-lying riverside areas, especially those outside permanent flood barriers, are urged to monitor conditions and move belongings to higher ground.
The Office of the National Water Resources (ONWR) has issued a warning for residents in low-lying riverside areas to monitor the risk of unusually high sea tides from January 2-9, as stronger northeast monsoon conditions could push seawater inland and cause flooding in communities outside permanent flood barriers.
ONWR said the current surge is being driven by two combined factors: an astronomically driven high-tide cycle and a strengthening northeast monsoon over the Gulf of Thailand, which can elevate sea levels above normal. This, in turn, may raise water levels in major river systems, including the Chao Phraya, Tha Chin and Mae Klong rivers.
Thailand’s Office of National Water Resources (ONWR) has issued a public warning for residents in low-lying riverside communities to closely monitor the risk of unusually high tides from January 2–9, 2026.
The agency said a combination of tidal conditions and a strengthening northeast monsoon over the Gulf of Thailand could push water levels higher than normal, raising the risk of flooding in communities outside flood embankments.
Why water levels may rise
ONWR said the current high-tide situation is being driven by two factors occurring at the same time:
- Seasonal high tides linked to astronomical cycles
- A stronger northeast monsoon, which can push seawater further inland and lift tide levels above normal
This may directly affect major rivers, including the Chao Phraya, Tha Chin, and Mae Klong, with water levels expected to rise above typical levels.
Seven provinces under close watch
ONWR said the following areas should closely track conditions due to the risk of sudden flooding:
- Bangkok
- Samut Prakan
- Nonthaburi
- Pathum Thani
- Samut Sakhon
- Nakhon Pathom
- Samut Songkhram
High-risk locations
People living in these areas were urged to prepare and move their belongings to higher ground:
- Low-lying riverbank areas, especially outside embankments
- Gaps in flood defences, where there are no permanent barriers or only temporary ones
- Downstream zones, where drainage into the sea may slow during high tide
Recommended precautions
ONWR advised residents to:
- Monitor updates regularly, including tide tables from the Royal Thai Navy’s Hydrographic Department
- Check temporary flood barriers and prepare sandbags in vulnerable spots
- Protect valuables and electrical points, moving items and power plugs above expected water levels, especially in homes close to rivers
The agency added that relevant authorities have been instructed to prepare water pumps and personnel to provide immediate assistance if an emergency occurs.
