| Saint-Louis | |
| Commune Status: | Commune |
| Map: | Locator map of Saint-Louis - Réunion 2018.png |
| Image Coat Of Arms: | Blason ville DomFr Saint-Louis (Réunion).svg |
| Arrondissement: | Saint-Pierre |
| Canton: | Saint-Louis-1 and 2 |
| Insee: | 97414 |
| Postal Code: | 97450 |
| Mayor: | Juliana M'Doihoma[1] |
| Term: | 2020 - 2026 |
| Intercommunality: | Villes solidaires |
| Coordinates: | -21.2867°N 55.4092°W |
| Elevation M: | 31 |
| Elevation Min M: | 0 |
| Elevation Max M: | 2543 |
| Area Km2: | 98.90 |
Saint-Louis (pronounced as /fr/; label=[[Réunion Creole|Reunionese Creole]]|Sin Loui) is the fifth-largest commune in the French overseas department of Réunion. It is located on the southwest part of the island of Réunion, adjacent to Saint-Pierre.
Saint-Louis has a tropical savanna climate (Köppen climate classification Aw). The average annual temperature in Saint-Louis is . The average annual rainfall is with January as the wettest month. The temperatures are highest on average in February, at around, and lowest in July, at around . The highest temperature ever recorded in Saint-Louis was on 11 February 2016; the coldest temperature ever recorded was on 10 August 2020.