The 2018–19 South Pacific cyclone season was a below-average season that produced 5 tropical cyclones, 2 of which became severe tropical cyclones. The season officially runs from November 1, 2018, to April 30, 2019; however, a tropical cyclone could have formed at any time between July 1, 2018, and June 30, 2019, and would count towards the season total. During the season, tropical cyclones were officially monitored by the Fiji Meteorological Service, Australian Bureau of Meteorology, and New Zealand's MetService. The United States Armed Forces through the Joint Typhoon Warning Center (JTWC) also monitored the basin and issued warnings for American interests. RSMC Nadi attaches a number and an F suffix to tropical disturbances that form in or move into the basin, while the JTWC designates significant tropical cyclones with a number and a P suffix. The FMS, the BoM and MetService all use the Australian Tropical Cyclone Intensity Scale and estimate wind speeds over a period of ten minutes, while the JTWC estimates sustained winds over a 1-minute period, which are subsequently compared to the Saffir–Simpson hurricane wind scale (SSHWS).

The 2018–19 South-West Indian Ocean cyclone season was the costliest and the most active season ever recorded. Additionally, it is also the deadliest cyclone season recorded in the South-West Indian Ocean, surpassing the 1891–92 season in which the 1892 Mauritius cyclone devastated the island of Mauritius, and is mainly due to Cyclone Idai. The season was an event of the annual cycle of tropical cyclone and subtropical cyclone formation in the South-West Indian Ocean basin. It officially began on 15 November 2018, and ended on 30 April 2019, except for Mauritius and the Seychelles, which it ended on 15 May 2019. These dates conventionally delimit the period of each year when most tropical and subtropical cyclones form in the basin, which is west of 90°E and south of the Equator. Tropical and subtropical cyclones in this basin are monitored by the Regional Specialised Meteorological Centre in Réunion.