December 5 is an important dual holiday in Thailand, marking both the birthday of the late King Bhumibol Adulyadej, considered to be the father of the nation, and National Father’s Day in his honor. The holiday is also known as Wan Por.

During the reign of King Bhumibol (King Rama IX), who passed away in 2016, December 5 was an annual public holiday when Thais celebrated the king’s birthday and wore yellow because he was born on Monday. Queen Sirikit’s birthday on August 12 is recognized as National Mother’s Day.