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 La Réunion.

January, however, was very active with four named systems developing (including Irving which entered the basin from the Australian region); Berguitta and Cebile in particular would become intense tropical cyclones on Météo-France La Réunion's scale.

[1] The season had a large-scale impact across Réunion, with five cyclones: Ava, Berguitta, Dumazile, Eliakim, and Fakir, affecting the island.

[4] Accumulating rainfall from the cyclones generated ravines which prevented employees from getting to work and caused significant damage to small-scale fishing operations, agriculture, roads, houses, and public infrastructure.

[6] A trail linking Bois Court and Grand Bassin was scheduled to reopen in April 2018 after having been closed since 12 February 2018.

Work to repair two bridges was halted as a result of a ban on large machinery in the river and threats of criminal prosecution against the workers.

Several items, including salads, zucchini, paracress, carrots, and tomatoes, were expected to have shortages or be entirely unavailable.

[14] In March 2019, the General Confederation of Planters and Breeders of Réunion Island requested that the agricultural minister to increase the dispersal rate for the aid package to help with recovery efforts.

[18] Agricultural experts anticipated that it would take months or years for farmers to recuperate the losses sustained during the cyclone season.

[19] MP David Lorion requested that the Réunion Prefecture government and the Minister of Overseas establish a relief fund to help repair damage sustained by floods and mudslides during cyclones Berguitta and Fakir.

The Communist Party of Réunion discussed implementing multiple improvements following the season, including redrawing risk areas and construction guidelines and adapting school schedules to the island's climate.

[22] The Réunion Prefecture government assembled a meeting of the mayors on 4 May 2018 to discuss implementing a new warning system for the next cyclone season.

[24] Repair work at the Bras de Cilaos following Berguitta was halted following torrential rainfall during Cyclone Dumazile.

Protests erupted in Cilaos because the postponement of work left 400 people isolated on the other side of the city and 100 more at Îlet Furçy.

Ava made landfall over Madagascar shortly after and reemerged over water as a weak tropical storm on 7 January.

[30][31] Flooding and landslides forced thousands of people to evacuate across the capital city of Antananarivo, Brickaville, Toamasina, Mananjary, and Ifanadiana.

[34] Tropical Cyclone Irving was named by the Bureau of Meteorology of Australia on 6 January as it crossed over into the South-West Indian Ocean basin a few hours later.

[44][45][46] Water utilities in the capital of Port Louis were disrupted by the storm,[47] and around 6,800 residences lost power as trees fell on electrical cables.

[57][58][59] Heavy rainfall and winds impacted Réunion on 18 January,[60] causing flooding and landslides across the southern region of the island.

[61] The storm broke several records for rainfall, most notably at Grande Coude, where 1,862 mm (73.3 in) of rain fell during an 8-day stretch.

[68] The only major highway connecting Cilaos with other towns was severed by multiple landslides,[69] bringing the local economy to a halt.

[70][71] The Réunion Prefecture government provided several million euros in relief aid,[72][73] however, reconstruction efforts were later disrupted by cyclones Dumazile and Fakir.

[78][79] Dumazile then began weakening as a result of increasing shear wind from a low-pressure system to the southwest and became post-tropical early on 7 March.

[citation needed] Dumazile halted recovery efforts that were ongoing after Cyclone Berguitta struck the island just two months prior, causing further damage.

[121][122] Toward the end of April, a westward-moving Rossby wave spawned a tropical low in the Australian basin southwest of Indonesia.

The low eventually intensified into the equivalent of a moderate tropical storm, whereupon TCWC Jakarta named it Flamboyan.

Thereafter, Flamboyan began weakening due to increased wind shear and cooler waters, while it curved to the south around a ridge.

[124][125][126][127][128] The first disturbance of this season, a low-pressure system, classified as a tropical low by the Australian Bureau of Meteorology,[129] moved west-southwestward across the 90th meridian east into the South-West Indian Ocean basin on August 8.

[130] At 10:00 UTC on the following day, Météo-France Réunion upgraded the low-pressure system to a zone of disturbed weather, with sustained winds of up to 55 km/h (35 mph) being detected on the southern side of the circulation by scatterometer.