Flames and smoke were noticed at the no-name bar behind the Sunwing Resort & Spa Phuket at Bang Tao about 11.50pm.
Cherng Talay police responded, along with two fire trucks. But a strong breeze helped the blaze to raze the bar, causing damaged estimated at 300,000 baht.
Owner Sanong Orndee, 59, was serving as a volunteer at a checkpoint in Phuket City while his wife Siriya Jaideesorrarot, 63, was asleep and did not know the bar was burning.
Forensic officers will take a closer look today but Khun Sanong said there was a dispute over the bar.