On September 24, 2025, various festivals and public holidays will be observed worldwide. In Cambodia, Constitution Day commemorates the re-coronation of King Norodom Sihanouk and the adoption of the country's constitution in 1993. The Dominican Republic celebrates Our Lady of Mercy Day, honoring the nation's patroness, Nuestra Señora de las Mercedes. Guinea-Bissau marks its National Day, celebrating independence from Portugal, while New Caledonia observes New Caledonia Day, marking its official colonization by France. In South Africa, Heritage Day focuses on celebrating the diverse cultures and traditions of its people. Additionally, Trinidad and Tobago recognizes Republic Day, commemorating its transition to a republic. Internationally, September 24 is also noted for observances such as World Cancer Research Day, aimed at promoting cancer research, and World Day Against Software Patents, advocating against software patents. Various cultural festivals, including the Oktoberfest in Munich, Germany, and the Odesa International Film Festival in Ukraine, will also take place on this date.