Thailand’s reservoirs held 83% of capacity on October 24
Western Thai reservoirs were 97% full on October 24, while a water agency warning identified 10 southern provinces at risk of flooding on October 23–26.
- As of October 24, Thailand's reservoirs held 66,788 million cubic metres of water, which is 83% of the country's total storage capacity.
- Regionally, Western Thailand's reservoirs had the highest storage at 97% of capacity, while the Northeast and South had the lowest at 70%.
- The four main dams in the Chao Phraya basin reported holding between 71% and 92% of their individual capacities.
- Due to the high water levels, authorities have called for close monitoring and careful management of water releases from reservoirs that are over 80% full.
The Office of the National Water Resources (ONWR) reported on October 25, 2026, that Thailand’s reservoirs held 66,788 million cubic metres of water, or 83% of storage capacity, as of October 24. The update came amid warnings of continued heavy rain in the South and flood risks in 10 southern provinces.
The ONWR called for close monitoring of large reservoirs holding more than 80% of capacity, with operators instructed to manage water and plan releases carefully to limit the impact on downstream communities.
Western reservoirs reach 97% of capacity
Western Thailand had the highest proportion of reservoir storage at 97% of capacity on October 24, followed by the East at 89%, according to the ONWR’s regional breakdown.
The ONWR reported the following storage volumes and proportions of capacity for October 24:
- North: 21,112 million cubic metres, or 77% of capacity.
- Northeast: 8,467 million cubic metres, or 70%.
- Central region: 1,348 million cubic metres, or 72%.
- East: 2,833 million cubic metres, or 89%.
- West: 27,578 million cubic metres, or 97%.
- South: 5,450 million cubic metres, or 70%.
Usable water nationwide stood at 42,661 million cubic metres as of October 24, according to the ONWR update.
Four main Chao Phraya basin dams hold 71–92% of capacity
Storage at the four main dams in the Chao Phraya basin ranged from 71% to 92% of capacity on October 24, according to the ONWR. The dams are central to water management in Thailand’s Central region.
The ONWR listed the following figures for October 24:
1. Bhumibol Dam, Tak: 9,542 million cubic metres, or 71% of capacity.
2. Sirikit Dam, Uttaradit: 7,767 million cubic metres, or 82%.
3. Khwae Noi Bamrung Dan Dam, Phitsanulok: 804 million cubic metres, or 86%.
4. Pa Sak Jolasid Dam, Lop Buri: 806 million cubic metres, or 92%.
Southern Thailand faces continued heavy rain through October 28
Southern Thailand was experiencing persistent rain, with isolated heavy to very heavy downpours, according to the ONWR’s October 25 assessment. The outlook for October 26–28 forecast continued rain, with heavy downpours in many areas and very heavy rain in some locations.
The ONWR’s October 25 assessment also forecast unsettled weather in upper Thailand, covering the North, Northeast, Central region and East, with thunderstorms, strong gusts and isolated heavy rain.
Trang recorded the highest regional rainfall maximum listed in the ONWR’s October 25 report, at 166 millimetres, prompting close monitoring of water conditions in the South.
The regional rainfall maxima in the October 25 report were:
- North: Nan, 72 millimetres.
- Northeast: Nakhon Ratchasima, 38 millimetres.
- Central region: Saraburi, 81 millimetres.
- East: Chachoengsao, 72 millimetres.
- West: Prachuap Khiri Khan, 50 millimetres.
- South: Trang, 166 millimetres.
ONWR identifies 10 southern provinces in October 23–26 flood warning
The ONWR’s warning for October 23–26 called on agencies and residents to prepare for standing floodwater, flash floods, rapid run-off and rivers overflowing their banks. The warning highlighted three priorities: vulnerable southern communities, large reservoirs above 80% of capacity, and sudden rises in rivers and tributaries.
The ONWR identified flood and landslide risks in the following 10 southern provinces during October 23–26:
- Ranong
- Phang Nga
- Phuket
- Surat Thani
- Nakhon Si Thammarat
- Phatthalung
- Songkhla
- Satun
- Yala
- Narathiwat
Residents in the provinces covered by the ONWR warning were advised to prepare and follow updates closely, particularly in foothill areas, along waterways and on low-lying ground.
For large reservoirs holding more than 80% of capacity, the ONWR instructed operators to step up water management and plan appropriate releases to protect downstream communities.
The ONWR also warned that sudden rises in major rivers and tributaries could cause overbank flooding and standing water in low-lying riverside areas. The waterways identified for monitoring during October 23–26 were:
- Western Thailand: The Khwae Noi, Khwae Yai and Phetchaburi rivers.
- Southern Thailand: The Tapi, Phum Duang, Takua Pa, Sai Buri and Kolok rivers, together with Tanyong Mat canal.
Residents in at-risk areas should follow warnings from the ONWR and the Thai Meteorological Department, move belongings to higher ground, prepare backup power supplies and take care when travelling on roads affected by heavy rain or standing water.
