| Country | National holiday |
| South Africa | Freedom Day, 27 April (1994) |
| South Georgia and the South Sandwich Islands | void |
| South Sudan | Independence Day, (9 July 2011) |
| Southern Ocean | void |
| Spain | National Day, 12 October (1492); year when Columbus first set foot in the Americas |
| Spratly Islands | void |
| Sri Lanka | Independence Day, 4 February (1948) |
| Sudan | Independence Day, 1 January (1956) |
| Suriname | Independence Day, 25 November (1975) |
| Svalbard | void |
| Swaziland | Independence Day, 6 September (1968) |
| Sweden | Swedish Flag Day, 6 June (1916); National Day, 6 June (1983) |
| Switzerland | Founding of the Swiss Confederation, 1 August (1291) |
| Syria | Independence Day, 17 April (1946) |
| Taiwan | Republic Day (Anniversary of the Chinese Revolution), 10 October (1911) |
| Tajikistan | Independence Day (or National Day), 9 September (1991) |
| Tanzania | Union Day (Tanganyika and Zanzibar), 26 April (1964) |
| Thailand | Birthday of King PHUMIPHON (BHUMIBOL), 5 December (1927) |
| Timor-Leste | Independence Day, 28 November (1975) |
| Togo | Independence Day, 27 April (1960) |
| Tokelau | Waitangi Day (Treaty of Waitangi established British sovereignty over New Zealand), 6 February (1840) |
| Tonga | National Day, 4 November (1875) |
| Trinidad and Tobago | Independence Day, 31 August (1962) |
| Tunisia | Independence Day, 20 March (1956) |