Date(s) - 18/06/2018
Norodom Monineath Sihanouk (Khmer: នរោត្ដម មុនីនាថ; born Paule Monique Izzi, 18 June 1936) is the queen mother of Cambodia. She was queen consort of Cambodia from 1952 to 1955 and again from 1993 to 2004, as the wife of King Norodom Sihanouk. She is the widow of King-Father Norodom Sihanouk, whom she married in 1952. Queen Monineath and King Sihanouk parented two children: Norodom Sihamoni (b. 1953) and Norodom Narindrapong (1954-2003). Her official, full title is “Preah Karuna Preah Bat Samdech Preah Mohaksatreyani Norodom Monineath Sihanouk” (Khmer: ព្រះករុណាព្រះបាទសម្តេចព្រះមហាក្សត្រិយានី នរោត្តម មុនិនាថ សីហនុ). The Queen is also called “Preah Voreakreach Meada Cheat Khmer” (Khmer: ព្រះវររាជមាតាជាតិខ្មែរ). Her birthday on 18 June is an official public holiday in Cambodia. Source.
If June 18 falls on a Saturday or Sunday, the following Monday is usually observed as a public holiday.