Previously, the agency's area of responsibility was limited to 80° E. It was an active season with twelve named storms, of which five strengthened into tropical cyclone with 10 minute sustained winds of at least 120 km/h (75 mph).

The strongest storm of the season, Erinesta, formed in late January and struck the tiny Tromelin Island, decimating the native rabbit population.

In March, Cyclone Honorinina killed 99 people and caused $150 million (1986 USD) in damage when it struck eastern Madagascar.

During the season, the Météo-France office (MFR) on Réunion island issued warnings in tropical cyclones within the basin.

Using satellite imagery from National Oceanic and Atmospheric Administration, the agency estimated intensity through the Dvorak technique, and warned on tropical cyclones in the region from the coast of Africa to 90° E, south of the equator.

In September 1985, their area of responsibility shifted from 80° E to the current 90° E, although lack of satellite imagery along the eastern periphery prevented complete coverage.

Classified as Tropical Cyclone 01S, the storm developed on September 23 to the east-southeast of Diego Garcia, which is an atoll in the central Indian Ocean.

[7] That day, the system reached peak winds of 65 km/h (40 mph),[8] and the Madagascar Meteorological Service named it Alifredy.

High pressures to the south prevented much development, and Alifredy moved ashore near Morondava in western Madagascar on December 24 at peak intensity.

[7] The Intertropical Convergence Zone (ITCZ) spawned a tropical depression in the northern periphery of the Mozambique Channel on January 5, near the Comoros.

Initially still located with the ITCZ, the system tracked south-southwestward, although its motion slowed due to a ridge to the south.

That night, the Madagascar Meteorological Service named the depression Berobia,[9] which intensified into a moderate tropical storm the next day.

[10] Late on January 9, Berobia made landfall about 125 km (75 mi) north of Beira, Mozambique, and it dissipated the next day after entering Zimbabwe.

Costa weakened briefly on January 14 while passing about 100 km (60 mi) east of Rodrigues, although it re-attained its former peak on the next day while accelerating southeastward.

[12] The monsoon was active in early January across the Indian Ocean, spawning what would eventually become Tropical Cyclone Delifina.

The system had a curved area of convection, and organized enough for MFR to designate it Tropical Storm Delifina on January 10.

[17] On the same day, the JTWC classified the storm as Tropical Cyclone 13S,[2] and the Mauritius Meteorological Service named it Erinesta.

[20] While moving past the island, Erinesta produced peak gusts of 139 km/h (86 mph) in the mountainous interior at Plaine des Cafres.

[21] In early February, an area of disturbed weather persisted around Diego Garcia, although lack of satellite imagery made it difficult to track the system at first.

[22] On February 6, satellite images indicated that a tropical storm formed,[23] given the name Filomena by the Mauritius Meteorological Service.

On February 11, the system turned westward and later northwest due to a ridge to the south, having weakened into a tropical depression.

The storm gradually intensified while moving away from the country, reaching peak 10 minute winds of 95 km/h (60 mph) on January 21 about 120 km (75 mi) east of Europa Island.

According to the JTWC, Gista intensified to the equivalent of a minimal hurricane on February 22 to the southwest of Madagascar, and the next day reached peak 1 minute winds of 160 km/h (100 mph).

[24][25] While Gista was moving along the west coast of Madagascar, it produced peak wind gusts of 82 km/h (51 mph) at Maintirano.

Honorinina weakened subsequently before making landfall about 40 km (25 mi) north of Toamasina, Madagascar with winds of 135 km/h (85 mph).

[26][27] Early in its duration, the storm produced gusty winds along St. Brandon, and it later brought gusts of 158 km/h (98 mph) on Tromelin Island.

In Toamasina, the cyclone damaged the main port, the airport, and several warehouses, resulting in $17 million (1986 USD) of lost inventory.

By that time, the motion shifted more to the southwest, bringing it 400 km (250 mi) east of Rodrigues; winds on the island remained less than 74 km/h (46 mph).

On the next day, the storm passed just north of the Cocos Islands, and the BoM upgraded Alison to the equivalent of a tropical cyclone.

[37] An eastward area of low pressure turned the storm to the southeast, crossing back into the Australian basin on April 13.