In Thailand, Father’s Day has traditionally been celebrated on December 5.
The date was chosen because December 5 was the birthday of King Bhumibol Adulyadej, who reigned as Thailand’s monarch from 1946 until his death in 2016. His long reign made the day an important national occasion as well as a family celebration.
Thai Father’s Day customs have included public ceremonies, family activities, and the presentation of canna flowers, which became associated with the holiday. The king was also symbolically regarded as the father of the nation, giving the date a civic meaning beyond honoring individual fathers.
A possible source of confusion is the change in Thailand’s royal calendar after King Bhumibol’s death. December 5 remains observed as Father’s Day, even though it is no longer the reigning king’s birthday. The date is therefore connected to the late monarch’s birthday and national tradition.