South-West Indian Ocean tropical cyclone
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In the south-west Indian Ocean, tropical cyclones form south of the equator and west of 90° E to the coast of Africa.
Warnings and nomenclature
In 1946, Réunion's first airstrip opened, then called Gillot, and now called Roland Garros Airport. In 1950, the first meteorological station on the island opened at the airport, operated by Météo-France (MFR). The agency began publishing annual reviews in the 1962–63 season. Each year, the Météo-France office (MFR) based on Réunion island issues warnings on tropical cyclones within the basin, which is defined as the waters of the Indian Ocean from the coast of Africa to 90° E, south of the equator. The agency issues the warnings as part of its role as a Regional Specialized Meteorological Center, designated as such in 1993 by the World Meteorological Organization. Intensities are estimated through the Dvorak technique, which utilizes images from satellites by the American National Oceanic and Atmospheric Administration.[1][2][3][4]
The Joint Typhoon Warning Center – a joint United States Navy – United States Air Force task force – also issues tropical cyclone warnings for the region.[5] Wind estimates from Météo-France and most other basins throughout the world are sustained over 10 minutes, while estimates from the United States–based Joint Typhoon Warning Center are sustained over 1 minute. 1-minute winds are about 1.12 times the amount of 10-minute winds.[6]
If a tropical storm in the basin strengthens to attain 10 minute sustained winds of at least 118 km/h (73 mph), the MFR classifies it as a tropical cyclone, equivalent to a hurricane or typhoon (a use of "tropical cyclone" which is more restrictive than the usual definition).[7]
History of the basin
The first storm in the MFR database of the basin originated on January 11, 1848. In January 1960, the first named storm was Alix, and each subsequent year had a list of storm names. Beginning in 1967, satellites helped locate cyclones in the basin, and in the following year, the MFR began estimating storm intensities from the satellite images. By 1977, the agency was using the Dvorak technique on an unofficial basis, but officially adopted it in 1981. Originally, the basin only extended to 80° E, and while it was extended eastward to the current 90° E, a lack of satellite imagery initially made data uncertain east of 80° E. The World Meteorological Organization designated the MFR as a Regional Tropical Cyclones Advisory Centre in 1988, and upgraded it to a Regional Specialized Meteorological Center in 1993. In May 1998, two Europe-based Meteosat satellites began providing complete coverage of the basin. On July 1, 2002, the MFR shifted the cyclone year to begin on this date and end on June 30 of the following year; previously, the cyclone year began on August 1 and ended on the subsequent July 31. In 2003, the MFR extended their area of warning responsibility to 40°S, having previously been limited to 30°S.[2] During 2011, MFR started a reanalysis project of all tropical systems between 1978 and 1998, with methods such as a Dvorak technique reanalysis and use of microwave imagery.[8] Preliminary results from this reanalysis project include correcting an increasing trend in the number of very intense tropical cyclones in the basin since 1978.[8] This also revealed a seemingly systematic underestimation of tropical cyclone intensities in the past.[8]
Statistics
From the 1980–81 to the 2010–11 season, there was an average of 9.3 tropical storms each year in the basin. A tropical storm has 10-minute winds of at least 65 km/h (40 mph). There are an average of five storms that become tropical cyclones, which have 10-minute winds of at least 120 km/h (75 mph).[9] As of 2002, there was an average of 54 days when tropical systems were active in the basin, of which 20 had tropical cyclones active, or a system with winds of over 120 km/h (75 mph). The median start date for the season was November 17, and the median end date was April 20.[1]
Climatology
Generally, the monsoon does not cross into the Mozambique Channel until December; as a result, storms rarely form there before that time.[1] From 1948 to 2010, 94 tropical systems developed in the small body of water, of which about half made landfall.[10] Occasionally, small storms form in the Mozambique Channel that resemble Mediterranean cyclones or storms in the northeastern Atlantic Ocean; these systems are well-organised but have weaker convection than typical tropical cyclones, and originate over sea surface temperatures cooler than 26 °C (79 °F). A survey in 2004 conducted by weather expert Gary Padgett found meteorologists divided over whether these storms should be classified as tropical or subtropical.[11]
In an average year, ten tropical depressions or storms strike Madagascar, and most generally do not cause much damage.[12] Occasionally, storms or their remnants move inland over southeastern Africa, bringing heavy rainfall to Zimbabwe.[13]
Seasons
25
50
75
100
125
150
Jan
Feb
Mar
Apr
May
Jun
Jul
Aug
Sep
Oct
Nov
Dec
|
Before 1900
1900–1950
1950–1959
1959
| Season | TD | TC | Strongest storm | Deaths | Damage USD | Notes and References |
|---|---|---|---|---|---|---|
| 1959–1960 | 6 | 8 | Carol | 48 | Features the first officially named tropical cyclone 'Alix' Included Carol which remains one of the most powerful storms in Mauritian history, with a central pressure of 942 hPa. It destroyed over 70,000 homes and led to the "Carol villages" housing reconstruction projects. |
1960s
| Season | TD | TC | Strongest storm | Deaths | Damage USD | Notes and References |
|---|---|---|---|---|---|---|
| 1960–1961 | 6 | 1 | Doris | Featured Cyclone Jenny, which is infamous for its rapid forward speed and no warning in advance for Mauritius. | ||
| 1961–1962 | 14 | 5 | Daisy Maud | |||
| 1962–1963 | 10 | 4 | TC Delia | |||
| 1963–1964 | 12 | 4 | ITC Giselle | Notable for Cyclone Danielle, which reached Very Intense status. It struck Madagascar’s east coast, causing significant loss of life and destroying substantial portions of the vanilla and coffee crops. | ||
| 1964–1965 | 14 | 1 | TC Freda | |||
| 1965–1966 | 17 | 5 | ITC Ivy | 3 | ||
| 1966–1967 | 13 | 2 | TC Gilberte | |||
| 1967–1968 | 8 | 4 | ITC Georgette ITC Janine | 38 | ||
| 1968–1969 | 8 | 4 | TC Dany TC Helene | 82 | ||
| 1969–1970 | 13 | 8 | VITC Jane | 30 |
1970s
| Season | TD | MTS | TC | ITC | VITC | Strongest storm | Deaths | Damage USD | Notes and References |
|---|---|---|---|---|---|---|---|---|---|
| 1970–1971 | 16 | 11 | 8 | 4 | 0 | ITC Maggie-Muriel | 32 | ||
| 1971–1972 | 9 | 7 | 2 | 1 | 0 | ITC Fabienne | 7 | Featured Fabienne, which struck Rodrigues and Mauritius. It was particularly destructive in Rodrigues, where it destroyed nearly 70% of the housing and caused severe agricultural losses. | |
| 1972–1973 | 13 | 11 | 4 | 2 | 1 | VITC Lydie | 11 | ||
| 1973–1974 | 8 | 7 | 1 | 0 | 0 | TC Deidre-Delinda | |||
| 1974–1975 | 10 | 6 | 2 | 0 | 0 | TC Gervaise | 9 | Marked by Cyclone Gervaise, one of the most famous storms in Mauritian history. It produced a record wind gust of 280 km/h at Mon Désert and led to a complete overhaul of building codes on the island. | |
| 1975–1976 | 8 | 6 | 1 | 1 | 0 | ITC Terry-Danae | |||
| 1976–1977 | 9 | 8 | 3 | 1 | 0 | ITC Jack-Io | 301 | ||
| 1977–1978 | 14 | 12 | 2 | 1 | 0 | ITC Aurore | 2 | ||
| 1978–1979 | 10 | 6 | 4 | 2 | 0 | ITC Celine | 74 | ||
| 1979–1980 | 11 | 11 | 4 | 2 | 0 | ITC Viola-Claudette | 30 | Featured, Hyacinthe, which holds the world record for the most rainfall from a single tropical system (over 6,000 mm on Réunion). |
1980s
| Season | TD | MTS | TC | ITC | Strongest storm | Deaths | Damage USD | Notes and References |
|---|---|---|---|---|---|---|---|---|
| 1980–81 | 12 | 10 | 3 | 2 | VITC Florine | Featured Cyclone Florine, which passed just north of Réunion. It produced immense rainfall, including a record-breaking 1,161 mm in 24 hours at Foc-Foc. | ||
| 1981–82 | 14 | 10 | 5 | 2 | ITC Chris-Damia | 100 | $250 million | |
| 1982–83 | 6 | 3 | 0 | 0 | STS Bemany and Elinah | 33 | $23 million | Least active season on record, tied with the 2010–11 season. Featured, Cyclone Elinah which made a rare and devastating landfall on the Comoro Islands (Comoros), causing significant damage to infrastructure. |
| 1983–84 | 14 | 11 | 4 | 4 | ITC Andry, Bakoly, Annette-Jaminy, and Kamisy | 356 | $496 million | Included Domoina caused 100-year floods in South Africa and record rainfall in Swaziland (now Eswatini). |
| 1984–85 | 9 | 9 | 1 | 0 | TC Helisaonina | 0 | Unknown | Helisaonina holds the record for the longest single name assigned in the basin at 11 characters. |
| 1985–86 | 13 | 13 | 5 | 1 | ITC Erinesta | 99 | $150 million | |
| 1986–87 | 10 | 8 | 1 | 0 | TC Daodo | 10 | $2 million | |
| 1987–88 | 11 | 11 | 4 | 1 | ITC Gasitao | 100 | $10 million | |
| 1988–89 | 12 | 11 | 6 | 0 | TC Leon-Hanitra and Krissy | 11 | $217 million | Notable for Cyclone Firinga, which struck Réunion in January 1989. It caused immense damage due to wind gusts exceeding 200 km/h and remains one of the "benchmark" storms for disaster preparedness on the island. |
| 1989–90 | 9 | 9 | 5 | 1 | ITC Walter-Gregoara | 46 | $1.5 million | |
| Totals | 110 | 95 | 34 | 11 | Chris-Damia | 755 | ≥$1.15 billion |
1990s
| Season | TD | MTS | TC | ITC | VITC | Strongest storm | Deaths | Damage USD | Notes and References |
|---|---|---|---|---|---|---|---|---|---|
| 1990–91 | 11 | 7 | 3 | 0 | 0 | TC Bella | 88 | ||
| 1991–92 | 14 | 11 | 3 | 1 | 0 | ITC Harriet-Heather | 2 | ||
| 1992–93 | 18 | 11 | 4 | 2 | 0 | ITC Edwina | 20 | Features, Cyclone Colina, which made a direct hit on Réunion. It was the first cyclone for the eye to track over the island since 1962[A 1][14] | |
| 1993–94 | 18 | 14 | 8 | 4 | 0 | ITC Geralda | 558 | Includes, Geralda which struck the island as a Category 5-equivalent storm. It is often called the "Cyclone of the Century" for Madagascar, killing over 200 people and destroying the homes of 500,000. | |
| 1994–95 | 20 | 11 | 5 | 3 | 0 | ITC Marlene | [15] | ||
| 1995–96 | 21 | 11 | 6 | 3 | 0 | ITC Bonita | 11 | [16] | |
| 1996–97 | 21 | 12 | 5 | 3 | 0 | ITC Daniella | 311 | $50 million | |
| 1997–98 | 16 | 5 | 1 | 0 | 0 | TC Anacelle | 88 | ||
| 1998–99 | 14 | 6 | 2 | 2 | 0 | ITC Evrina | 2 | ||
| 1999–00 | 14 | 9 | 4 | 3 | 1 | VITC Hudah | 1,073 | $800 million | The fourth deadliest season on record. Cyclone Hudah, one of the deadliest, with over 1,000 fatalities across Mozambique and Madagascar.[17] |
| Totals | 167 | 97 | 41 | 21 | 1 | Hudah | 2,153 | ≥$850 million |
2000s
| Season | TD | MTS | TC | ITC | VITC | Strongest storm | Deaths | Damage USD | Notes and References |
|---|---|---|---|---|---|---|---|---|---|
| 2000–01 | 11 | 6 | 4 | 2 | 0 | ITC Ando | 4 | [A 1][18] | |
| 2001–02 | 15 | 11 | 9 | 5 | 1 | VITC Hary | 52 | $287 million | [19] |
| 2002–03 | 14 | 12 | 7 | 3 | 0 | ITC Kalunde | 169 | $6.7 million | Notable for Dina, which caused significant damage to Mauritius and Réunion.[A 1] |
| 2003–04 | 15 | 10 | 5 | 3 | 1 | VITC Gafilo | 396 | $250 million | This season featured the most intense storm on record in the basin, Gafilo.[20][21] |
| 2004–05 | 18 | 10 | 4 | 3 | 1 | VITC Juliet | 253 | [21] | |
| 2005–06 | 13 | 6 | 3 | 2 | 0 | ITC Carina | 75 | [22][23] | |
| 2006–07 | 15 | 10 | 7 | 6 | 0 | ITC Dora and Favio | 188 | $337 million | [A 1][23] |
| 2007–08 | 15 | 13 | 6 | 4 | 0 | ITC Hondo | 123 | $38.1 million | Notable for Ivan, which made a catastrophic landfall on Sainte-Marie Island and mainland Madagascar as an Intense Tropical Cyclone, killing nearly 100 people and leaving 190,000 homeless.[23] |
| 2008–09 | 12 | 10 | 2 | 2 | 0 | ITC Fanele and Gael | 30 | [24] | |
| 2009–10 | 16 | 9 | 5 | 4 | 1 | VITC Edzani | 40 | [A 1][24][25] | |
| Totals | 144 | 97 | 52 | 34 | 4 | Gafilo | 1,339 | ≥$919 million |
2010s
| Season | TD | MTS | TC | ITC | VITC | Strongest storm | Deaths | Damage USD | Notes and References |
|---|---|---|---|---|---|---|---|---|---|
| 2010–11 | 9 | 3 | 2 | 0 | 0 | TC Bingiza | 34 | Least active season on record, tied with the 1982–83 season.[A 1][26] | |
| 2011–12 | 14 | 10 | 3 | 2 | 0 | ITC Funso | 164 | [A 1][26] | |
| 2012–13 | 11 | 10 | 7 | 3 | 0 | ITC Felleng | 35 | $46 million | |
| 2013–14 | 15 | 11 | 5 | 5 | 2 | VITC Hellen | 11 | $89.2 million | One of the fastest intensifying storms in the Mozambique Channel, Hellen. |
| 2014–15 | 14 | 11 | 4 | 3 | 2 | VITC Bansi | 111 | $46.4 million | |
| 2015–16 | 8 | 8 | 3 | 3 | 1 | VITC Fantala | 13 | $4.5 million | Features the strongest storm by windspeed recorded in the basin, Fantala.[27] |
| 2016–17 | 7 | 5 | 3 | 1 | 0 | ITC Enawo | 341 | $137 million | |
| 2017–18 | 9 | 8 | 6 | 3 | 0 | ITC Cebile | 108 | $38.2 million | |
| 2018–19 | 15 | 15 | 11 | 9 | 0 | ITC Kenneth | 1,672 | ≥$3.65 billion | Most active, second costliest, and deadliest season on record Features Idai, deadliest cyclone on record and second costliest in basin history. Includes Kenneth, the strongest tropical cyclone to make landfall in Mozambique since modern records began. |
| 2019–20 | 12 | 10 | 6 | 3 | 1 | VITC Ambali | 45 | $25 million | Includes Ambali, the fastest intensification in the Southern Hemisphere, strengthening from a Tropical Depression to a Very Intense Tropical Cyclone in just 24 hours. |
| Totals | 112 | 89 | 49 | 32 | 6 | Fantala | 2,244 | ≥$2.7 billion |
2020s
| Season | TD | MTS | TC | ITC | VITC | Strongest storm | Deaths | Damage USD | Notes and References |
|---|---|---|---|---|---|---|---|---|---|
| 2020–21 | 16 | 12 | 7 | 2 | 2 | VITC Faraji VITC Habana | 56 | $90.1 million | Features two very intense tropical cyclones named in the basin. Record third consecutive season for a storm to develop before the official start (Alicia). |
| 2021–22 | 13 | 12 | 5 | 5 | 0 | ITC Batsirai | 376 | $380 million | Latest start to an SWIO season. |
| 2022–23 | 10 | 9 | 5 | 3 | 2 | VITC Darian | 1,483 | >$1.55 billion | Features two very intense tropical cyclones named in the Australian Region. Features Freddy, the longest lasting tropical cyclone ever recorded. Third deadliest season. |
| 2023–24 | 12 | 10 | 7 | 2 | 0 | ITC Djoungou | 25 | $536 million | Features Belal, the first to make landfall over Réunion since Hondo in 2008, and the strongest to strike the island since Firinga in 1989. |
| 2024–25 | 15 | 13 | 9 | 6 | 1 | VITC Vince | 189+ | >$4.1 billion | Features Bheki, the most intense off-season tropical cyclone since Beni in 2003. Features Chido, the strongest system to ever make landfall on Mayotte since records began. Features Kanto, the first officially named subtropical storm in basin history. Costliest South-West Indian Ocean cyclone season on record. Tied as the third-busiest season in the South-West Indian Ocean. |
| 2025–26 | 13 | 11 | 6 | 4 | 0 | ITC Horacio | 75+ | >$2.48
billion |
Notable for three pre-season storms and one depression (01, Awo, Blossom, and Chenge) which developed between July and October. Features Awo, the first named storm to develop in August since Aline in 1969. Features Gezani, a catastrophic storm for Toamasina, where approximately 75% of buildings were reportedly destroyed. It caused an estimated $2 billion in damage to Madagascar alone, was also the costliest storm to hit Madagascar on record and the third costliest storm in the basin on record. Features Juluka, the second officially named subtropical storm in basin history, following Kanto from the 2024–25 season Third costliest South-West Indian Ocean cyclone season on record. |
| Totals | 78 | 67 | 39 | 22 | 5 | Darian | 2,204+ | >$9.136 billion | |
See also
Notes
- Number of tropical storms includes one subtropical depression that had winds above 65 km/h (40 mph).