UPDATE: Pua floods cut three highway sections as coastal wave watch expands to seven provinces

More than 110mm of overnight rain in the Doi Phu Kha headwater area triggered flash floods in Pua district, Nan, on Wednesday, 19 August 2026, inundating homes and cutting three highway sections, Nation Thailand reported. All districts in Phuket remain under a rough-sea warning through 21 August 2026, while the Department of Disaster Prevention and Mitigation (DDPM) monitors flash-flood, landslide and waterlogging risks across 39 provinces.

The Doi Phu Kha National Park office recorded more than 110mm of rain overnight in Phu Kha subdistrict, a forested headwater area. Rapid runoff spread through Pua, damaging farmland and sending floodwater into homes. In some locations, water reached almost the level of a second storey. Residents moved belongings, electrical appliances and pets to higher ground as the flooding worsened. Ban Rong in Pua subdistrict was among the badly affected areas.

Nan Highway District 2, under the Department of Highways, identified three highway points that vehicles could not pass. Highway 101 was impassable at kilometre 429+750 on the Chang Phueak intersection–Pua section, before Ban Rong Bridge. Highway 1371 was closed at kilometre 0+500 on the Tin Tok–Ban Mon section at Ban Fai Bridge, while Highway 1256 was impassable at kilometre 6+000 on the Pua–Doi Phu Kha National Park section after a bridge was washed away.

At least two bridges were washed away. The reports specifically mentioned a bridge at Ban Na Lae and another in the Fai Chao weir area. Landslides were also reported at several locations in Ouan subdistrict, blocking roads as officials worked to reach affected communities. Travellers heading towards Pua were advised to avoid the affected routes.

A separate Nation Thailand situation report on 19 August said sustained heavy rain had caused flash floods, waterlogging, road closures, landslides and fallen trees across Nan, damaging homes, roads and transport routes. Pua, Mae Charim and Santi Suk districts were affected. In Pua, nine subdistricts and 35 villages were affected, covering about 8,000 households and 16,000 people. That report said five road routes had been cut and evacuation centres had been established, while routes in Pua, Phu Phiang and Santi Suk were impassable to vehicles.

The DDPM, working with mobile network operators AIS, True and NT, sent a Cell Broadcast Extreme Alert specifically to Pua district. The warning said heavy rain was continuing, with risks of flash floods, overflowing waterways and landslides. Residents were told to move belongings to higher ground immediately and relocate vulnerable people, including older people and bedridden patients. Anyone needing evacuation or assistance was told to contact their subdistrict chief, village head or local administrative organisation.

On Thursday, 20 August, Nation Thailand reported that the DDPM had sent Cell Broadcast flood alerts to communities in northern and northeastern provinces as persistent rain continued to raise the risks of flash floods, runoff, waterlogging, overflowing waterways and landslides. The DDPM continued monitoring landslide risks. Residents were urged to move household items and vehicles to safer ground, secure valuables and important documents, avoid electrical hazards and assist vulnerable people.

Meanwhile, the Nan River continued to rise across the province and had begun overflowing its banks in Tha Wang Pha. Water levels in Mueang Nan and Phu Phiang were also rising and could spill over. The DDPM issued Cell Broadcast warnings in the three districts: an Extreme Alert for flooding in Tha Wang Pha and Informational Alerts for rising water in Mueang Nan and Phu Phiang.

Residents living beside the river or its tributaries in Tha Wang Pha were told to move belongings to higher ground immediately and relocate vehicles to safe areas. Vulnerable people were advised to move to safer locations. Anyone requiring evacuation support was told to contact their subdistrict chief, village head or local administrative organisation.

Nation Thailand also reported that floodwaters were expected to move towards Tha Wang Pha and Mueang Nan on Thursday, 20 August, before continuing towards Wiang Sa on Friday, 21 August. Mueang Nan and Wiang Sa were to remain on maximum alert on those days. Municipalities advised residents to move belongings to higher ground and prepare to evacuate vulnerable people.

Deputy Interior Minister Jeseth Thaiseth chaired a meeting of the Central Disaster Prevention and Mitigation Command on Wednesday, 19 August, to oversee relief operations in Nan and prepare for further flooding across the North. Officials were ordered to relocate vulnerable people, handle requests for assistance and monitor social media for people seeking help. Nan’s provincial team was directed to take command at the scene.

Separately, Nation Thailand reported that Deputy Prime Minister Yodchanan Wongsawat had signed an urgent directive instructing the governors of Nan, Phayao and Lamphun to activate flood plans, prepare Cell Broadcast warnings and maintain round-the-clock readiness for flooding, flash floods and runoff.

The directive required authorities to coordinate information from upstream areas and neighbouring provinces, issue timely warnings, and pre-position personnel, boats, pumps and other response equipment at high-risk locations. Temporary shelters were to be prepared with food, drinking water and public-health services, while field kitchens and supplies were to be made ready for displaced residents. The provinces were also told to establish incident command centres if flooding occurred and prioritise vulnerable people.

DDPM units in the lower North were ordered to send jet skis and flat-bottomed boats to Nan, while a KA-32 disaster-relief helicopter was kept on standby. The directive specified that the helicopter could be used to evacuate people and deliver relief supplies to areas that are difficult to reach by land.

Military, DDPM and volunteer teams were deployed, and about 70 to 80 military personnel were working to evacuate residents trapped in homes in the Ban Rong area. The Jet Ski Association of Thailand also sent a team with eight jet skis from Bangkok.

The Department of Highways, police and local volunteers were asked to provide escorts and deploy vehicles, tools, drinking-water production trucks, mobile kitchens and personnel. Authorities were also told to monitor conditions around the clock because continued rain could affect more areas.

The DDPM said the wider warning followed a Thai Meteorological Department forecast of heavy to very heavy rain caused by a monsoon trough over northern and upper northeastern Thailand and a strong southwesterly monsoon over the Andaman Sea, Thailand and the Gulf of Thailand. The flash-flood and landslide warning covers 39 provinces in the North, Northeast and Central regions from 18 to 21 August.

Sea conditions in the upper Andaman Sea were expected to strengthen from 19 to 21 August, with waves of 2–3 metres and waves higher than 3 metres during thunderstorms. Waves in the lower Andaman Sea and the upper Gulf of Thailand could reach about 2 metres, rising above that level in thundery areas.

The earlier rough-sea alert covered all districts in Phuket through 21 August, as well as parts of Ranong and Phang Nga. In Phang Nga, the affected districts are Khura Buri, Takua Pa, Thai Mueang, Takua Thung and Ko Yao.

In its 20 August update, the DDPM also advised close surveillance for strong winds and waves in seven coastal provinces: Chon Buri, Rayong, Chanthaburi, Trat, Ranong, Phang Nga and Phuket. This is a broader close-surveillance scope than the specific rough-sea coverage described above; the two notices should not be treated as identical.

The DDPM has instructed authorities to monitor weather, rainfall and local water levels, deploy response teams and machinery in vulnerable areas, and prepare temporary shelters where necessary. Locations with accumulated rainfall above 90 millimetres in 24 hours and areas with a history of repeated flooding are to receive particular attention.

Authorities have also been told to monitor caves, waterfalls and other natural tourist attractions, issuing warnings or closing access if conditions become dangerous. In coastal areas, agencies are to install warning signs, prevent visitors from entering the water during dangerous conditions and advise boat and passenger-transport operators to exercise caution. Boat services may be suspended if conditions deteriorate.

The public is advised to follow official weather and disaster announcements. Assistance is available through the THAI DISASTER ALERT application, the DDPM 1784 LINE account (@1784DDPM) and the 1784 disaster prevention hotline.