1979–80 South-West Indian Ocean cyclone season
Season summary map
Seasonal boundaries
First system formed	August 30, 1979
Last system dissipated	March 20, 1980
Strongest storm
Name	Viola-Claudette
• Maximum winds	205 km/h (125 mph) (10-minute sustained)
• Lowest pressure	930 hPa (mbar)
Seasonal statistics
Total depressions	11
Total storms	11
Tropical cyclones	4
Intense tropical cyclones	2
Total fatalities	30
Total damage	$342 million (1980 USD)
Related articles
1979–80 Australian region cyclone season 1979–80 South Pacific cyclone season
South-West Indian Ocean tropical cyclone seasons 1977–78, 1978–79, 1979–80, 1980–81, 1981–82

The 1979–80 South-West Indian Ocean cyclone season was an above-average cyclone season, and is most notable for featuring the wettest tropical cyclone ever recorded, Cyclone Hyacinthe. The season officially ran from November 1, 1979, to April 30, 1980.

Category 2 tropical cyclone (Australian scale)
Duration	August 27 – August 31
Peak intensity	95 km/h (60 mph) (10-min); 990 hPa (mbar)

On 26 August, the BoM reported that a tropical low had developed on a shear line about 1300 km (810 mi) to the northwest of Cocos Island.^[1] Over the next couple of days the depression gradually developed further before at 1800 UTC on 27 August, TCWC Perth estimated that it had become a tropical cyclone and named it Tony.^[1] During the next couple of days, the system moved towards the west-southwest before on 29 August it reached its peak intensity of 95 km/h (60 mph) and a peak pressure of 990 hPa (29.23 inHg) as it approached the edge of TCWC Perth's area of responsibility.^[1] During the next day, Tony moved into the South West Indian Ocean and weakened gradually before it dissipated during 31 August.^[1] Neither the Mauritius or Reunion meteorological services monitored Tony as a tropical cyclone while it was active, while it was not included in the JTWC's analysis of the season.^[1][2][3]

Intense tropical cyclone (MFR)
Category 2 tropical cyclone (SSHWS)
Duration	November 25 – December 6
Peak intensity	195 km/h (120 mph) (10-min); 960 hPa (mbar)

Albine existed from 25 November to 6 December.

Intense tropical cyclone (MFR)
Category 3 tropical cyclone (SSHWS)
Duration	December 18 (Crossed 80°E) – December 28
Peak intensity	215 km/h (130 mph) (10-min); 955 hPa (mbar)

Cyclone Viola entered the basin on December 18 from the Australian region, whereupon it became Cyclone Claudette.^[4] After passing southeast of St. Brandon, Claudette struck Mauritius on December 22, producing wind gusts of 221 km/h (137 mph). The storm caused 5 fatalities, 257 injuries, and US$175 million in damage on the island. About 5,000 houses were destroyed or severely damaged. Effects on neighboring Réunion were limited to 79 km/h (49 mph) wind gusts and some rainfall.^[5][6][7][8]

Moderate tropical storm (MFR)
Tropical storm (SSHWS)
Duration	December 15 – December 21
Peak intensity	65 km/h (40 mph) (10-min); 1000 hPa (mbar)

Berenice existed from 15 December to 21 December.

Tropical depression (MFR)
Tropical storm (SSHWS)
Duration	December 23 – January 3
Peak intensity	55 km/h (35 mph) (10-min); 1000 hPa (mbar)

Wilf-Danitza existed from 23 December 1979, to 3 January 1980.

Intense tropical cyclone (MFR)
Category 1 tropical cyclone (SSHWS)
Duration	January 15 – January 31
Peak intensity	165 km/h (105 mph) (10-min); 960 hPa (mbar)

Hyacinthe formed on January 15, 1980, to the northeast of Mauritius in the southern Indian Ocean. Initially it moved to the west-southwest, and while slowly intensifying it passed north of the French overseas department of Réunion. On January 19, Météo-France estimated that the storm had intensified to a tropical cyclone. Hyacinthe looped to the south of eastern Madagascar and weakened, although it restrengthened after turning to the east. The storm executed another loop to the southwest of Réunion, passing near the island for a second and later third time. Hyacinthe became extratropical on January 29 after turning southward, dissipating two days later.

Tropical Cyclone Hyacinthe set several worldwide tropical cyclone rainfall records in Réunion in the Southwestern Indian Ocean, including a peak total of 5678 mm (223.5 inches).^[9] For twelve days, Hyacinthe dropped torrential rainfall on Réunion; nearly all of the island received more than 1 m (3.3 ft) of precipitation. Over a 15‑day period from January 14 to January 28, 6,083 mm (239.5 in) of rainfall were recorded at Commerson's Crater, a volcano. The heaviest rainfall occurred through a process called orographic lift in the mountainous interior, leading to hundreds of landslides. Widespread floods washed out roads and isolated three villages. Hyacinthe caused heavy damage to crops and damaged or destroyed 2,000 houses. Losses from the storm totaled $167 million (1980 USD, 676 million francs), and 25 people were killed.

Intense tropical cyclone (MFR)
Category 3 tropical cyclone (SSHWS)
Duration	February 1 – February 7
Peak intensity	185 km/h (115 mph) (10-min); 955 hPa (mbar)

Jacinthe existed from 1 February to 7 February. On February 3, the cyclone passed between Mauritius and Rodrigues, producing wind gusts of 117 km/h (73 mph) and 119 km/h (74 mph) on the respective islands.^[10]

Severe tropical storm (MFR)
Tropical storm (SSHWS)
Duration	February 25 – March 13
Peak intensity	110 km/h (70 mph) (10-min); 985 hPa (mbar)

Kolia existed from 25 February to 13 March. The storm executed two loops near the Mascarene Islands, bringing the storm between Réunion and Mauritius twice. Wind gusts reached 80 km/h (50 mph) on Mauritius.^[11]

Intense tropical cyclone (MFR)
Category 3 tropical cyclone (SSHWS)
Duration	March 8 – March 17
Peak intensity	165 km/h (105 mph) (10-min); 965 hPa (mbar)

Laure existed from 8 March to 17 March. On March 13, the cyclone passed just east of Mauritius, producing wind gusts of 109 km/h (68 mph) and 65.7 mm (2.59 in) of rainfall.^[12]

Moderate tropical storm (MFR)
Tropical storm (SSHWS)
Duration	March 14 – March 20
Peak intensity	85 km/h (50 mph) (10-min);

22S existed from 14 March to 20 March.

• Atlantic hurricane seasons: 1979, 1980
• Eastern Pacific hurricane seasons: 1979, 1980
• Western Pacific typhoon seasons: 1979, 1980
• North Indian Ocean cyclone seasons: 1979, 1980