Thailand faces prolonged dry spells as El Niño drives erratic weather patterns

The National Water Resources Office (NWRO) has warned the public to closely monitor water conditions after identifying signs that Thailand is set to enter a prolonged dry spell from late June to mid-July 2026, with El Niño conditions expected to drive increasingly erratic weather throughout the year.

Chayan Muangsong, Secretary-General of the NWRO, said data from the Meteorological Department and the Hydro-Informatics Institute indicates that although Thailand remains in the rainy season, a “rain gap” is expected between late June and mid-July 2026 as a low-pressure trough shifts northwards over southern China.

He added that the situation is more concerning because ENSO conditions have already transitioned into El Niño, which climate models suggest will persist through the year. This is expected to intensify dry spells and extend weather variability, leading to heatwaves, drought in some areas, as well as episodes of heavy rainfall and localised flooding.

Reservoir levels below last year

Overall rainfall and water conditions since the start of the year remain below average and require close monitoring:

• Rainfall is around 10% below the long-term average
• Total water storage in 35 major reservoirs nationwide stands at 45.05 billion cubic metres, or 56% of total capacity
• Usable water volume is 20.94 billion cubic metres, or 37% of capacity
• This is 490 million cubic metres lower than the same period last year

Despite lower-than-average rainfall, the NWRO warned that heavy rainfall events could still occur, potentially triggering flash floods, runoff and landslides in some regions.

The agency has instructed all relevant bodies to strictly implement nine key rainy-season preparedness measures for 2026, and to ensure machinery and personnel are ready for rapid emergency response.

In terms of water management, the NWRO is coordinating with the Royal Irrigation Department and the Electricity Generating Authority of Thailand (EGAT) to adjust water release plans in line with real-time conditions, ensure balanced water distribution, and prioritise water storage after the rainy season for future use.

The office is also encouraging the public to use water responsibly.

In addition, the NWRO continues to monitor and analyse weather conditions twice daily, morning and evening, to issue timely warnings. It is also developing a new rainfall forecasting model for submission to the Subcommittee on Water Resources Management.

The upgraded model is expected to improve flood and landslide risk prediction and enhance the accuracy of water-flow analysis in the future.