December 5th, was the date of the anniversary of the King Bhumibol Adulyadej, Rama IX, (its dynastic name), born in 1927, who died on 13th October 2016. He was the Father of the nation and this date also became Father's Day in Thailand.
The day may change but for now December 5 remains Father's Day in Thailand.
With a lot of traditions, festivals in Thailand are numerous and some are worldwide famous. Loy Krathong sometimes also called the Festival of Lights is held in November and was elected second best festival in the world. It must be said that this is the most photogenic festival in Thailand.
The main events of the Buddhist calendar but also the anniversaries of the King and Queen of Thailand and other days related to the History of the country are holidays in Thailand. If banks and administrations are generally closed those days, transport, shops and restaurants operate normally.