From Tourist Authority Thailand (TAT) :
"Today 13 October 2016 Thailand's King Bhumibol Adulyadej, the world's longest-reigning monarch, has died after 70 years on the throne. All sectors in the society are urged to refrain from holding entertainment activities for 1 month. All government agencies are ordered to fly half-mast for 1 month. And government officials are ordered to wear black for 1 year. More information will follow via the official channels of the Thai government. See also The Nation - Thailand's English Newspaper
Update : Travel Advisory (14 October 2016) Following the official announcement of the death of His Majesty King Bhumibol Adulyadej there is now an official period of mourning of one year from 14 October 2016; you should respect the feelings and sensitivities of the Thai people at this time; access to entertainment, including restaurants and bars areas may be restricted and you should behave respectfully when in public areas; if possible, wear sombre and respectful clothing when in public for the first month; check local media regularly and follow the advice of the local authorities. Do not take this lightly as there might be strict law-enforcement."