The 1974–75 South-West Indian Ocean cyclone season was a below-average cyclone season. The season officially ran from November 1, 1974, to April 30, 1975.

Systems

Tropical Disturbance Adele

Adele existed from December 23 to December 24.

Intense Tropical Cyclone Blandine

Blandine existed from January 6 to January 12.

Tropical Cyclone Camille

This system formed southeast of the Seychelles on January 7 before becoming disorganized while interacting with northern Madagascar. The system redeveloped as a hurricane-force cyclone in the northern Mozambique Channel on January 16 before moving southeast into Madagascar on January 19.

Intense Tropical Cyclone Robyn–Deborah

This system existed from January 14 to January 24.

Tropical Depression Elsa

Elsa existed from January 25 to January 27.

Tropical Disturbance Fernande

This storm lasted for only 18 hours on February 1.

Very Intense Tropical Cyclone Gervaise

The origins of Cyclone Gervaise were in early February 1975 from a circular area of

convection Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy). When the cause of the convec ...

, or thunderstorms, located in the

Intertropical Convergence Zone The Intertropical Convergence Zone (ITCZ ), known by sailors as the doldrums or the calms because of its monotonous windless weather, is the area where the northeast and the southeast trade winds converge. It encircles Earth near the thermal e ...

southwest of

Diego Garcia Diego Garcia is an island of the British Indian Ocean Territory, a disputed overseas territory of the United Kingdom. It is a militarised atoll just south of the equator in the central Indian Ocean, and the largest of the 60 small islands o ...

in the south-west

Indian Ocean The Indian Ocean is the third-largest of the world's five oceanic divisions, covering or ~19.8% of the water on Earth's surface. It is bounded by Asia to the north, Africa to the west and Australia to the east. To the south it is bounded by th ...

. The system organized as it moved generally to the southwest, a trajectory it would maintain for several days due to a

subtropical ridge The horse latitudes are the latitudes about 30 degrees north and south of the Equator. They are characterized by sunny skies, calm winds, and very little precipitation. They are also known as Subtropics, subtropical ridges, or highs. It is a h ...

to its southeast, and an area of low pressure near the

Mascarene Islands The Mascarene Islands (, ) or Mascarenes or Mascarenhas Archipelago is a group of islands in the Indian Ocean east of Madagascar consisting of the islands belonging to the Republic of Mauritius as well as the French department of Réunion. Thei ...

. On February 2, the Mauritius Meteorological Services named the storm ''Gervaise''. Two days later, the storm attained hurricane status, or

maximum sustained winds The maximum sustained wind associated with a tropical cyclone is a common indicator of the intensity of the storm. Within a mature tropical cyclone, it is found within the eyewall at a distance defined as the radius of maximum wind, or RMW. Unl ...

of at least . Late on February 5, Gervaise passed about 100 km (60 mi) southeast of

St. Brandon It is highly likely that the name Saint Brandon was derived from the French sailors and corsairs that sailed to and from Britanny, after a town called Saint-Brandan. It has since been Anglicised to Saint Brandon and is also known as the Cargad ...

. Continuing southwestward, the cyclone struck

Mauritius Mauritius ( ; french: Maurice, link=no ; mfe, label=Mauritian Creole, Moris ), officially the Republic of Mauritius, is an island nation in the Indian Ocean about off the southeast coast of the African continent, east of Madagascar. It incl ...

on February 6, with the calm of the eye lasting for three hours. That day, the American-based

Joint Typhoon Warning Center The Joint typhoon Warning Center (JTWC) is a joint United States Navy – United States Air Force command in Pearl Harbor, Hawaii. The JTWC is responsible for the issuing of tropical cyclone warnings in the North-West Pacific Ocean, South P ...

(JTWC) estimated peak winds of . On February 7, Gervaise passed about southeast of Réunion. The track shifted to the south and southeast over time, steered by a passing

cold front A cold front is the leading edge of a cooler mass of air at ground level that replaces a warmer mass of air and lies within a pronounced surface trough of low pressure. It often forms behind an extratropical cyclone (to the west in the Norther ...

. On February 10, Gervaise dissipated within the cold front. Gervaise first affected St. Brandon, producing wind gusts of over , along with heavy rainfall. Cyclone Gervaise killed 10 people during its passage of Mauritius. Its strongest wind gusts occurred after the passage of the eye, peaking at at Mon Desert. Heavy rainfall affected the island for several days, reaching at Grosse Roche. The high winds knocked down power lines, radio transmission with

Vacoas Vacoas-Phoenix () also known as French: ''Villes Jumelles'' (Twin Cities), is a town in Mauritius, located in the Plaines Wilhems District, the eastern part also lies in the Moka District. The town is administered by the Municipal Council of Vaco ...

for 24 hours, and many crops. About 25% of the island's sugar cane crop was lost. The storm damaged several houses, leaving thousands homeless. The cyclone last affected Réunion, where it produced wind gusts of . Gervaise also dropped heavy rainfall on the island, reaching at

Plaine des Cafres The Plaine des Cafres is a plateau on Réunion Island, one of the French volcanic islands in the Mascarene Archipelago in the southwestern Indian Ocean. It is part of the commune of Le Tampon. It is named after the Cafres, black slaves who hi ...

. It caused substantial damage to properties, vegetation and wildlife. Moored yachts around the coast were washed hundreds of yards inland in places due to the storm surge and in the Mauritian capital Port Louis, a cargo ship of ca. 10,000 tonnes was washed up on to the quay. 34 injured, 3,706 homeless.

Tropical Cyclone Helose

Helose existed from February 19 to February 26.

Severe Tropical Storm Ines

Ines existed from March 9 to March 19.

Severe Tropical Storm Junon

Junon existed from April 18 to April 22.

Season effects

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Notes

References

{{DEFAULTSORT:1974-75 Southern Hemisphere tropical cyclone seasons South-West_Indian_Ocean South-West Indian Ocean cyclone seasons