An Australian region tropical cyclone is a non-frontal, low-pressure system that has developed within an environment of warm sea surface temperatures and little vertical wind shear aloft in either the Southern Indian Ocean or the South Pacific Ocean. [1] Within the Southern Hemisphere there are officially three areas where tropical cyclones develop on a regular basis: the South-West Indian Ocean between Africa and 90°E, the Australian region between 90°E and 160°E, and the South Pacific basin between 160°E and 120°W. The Australian region between 90°E and 160°E is officially monitored by the Australian Bureau of Meteorology, the Indonesian Meteorology, Climatology, and Geophysical Agency, and the Papua New Guinea National Weather Service, while others like the Fiji Meteorological Service and the United States National Oceanic and Atmospheric Administration also monitor the basin. Each tropical cyclone year within this basin starts on 1 July and runs throughout the year, encompassing the tropical cyclone season, which runs from 1 November and lasts until 30 April each season. Within the basin, most tropical cyclones have their origins within the South Pacific convergence zone or within the Northern Australian monsoon trough, both of which form an extensive area of cloudiness and are dominant features of the season. Within this region a tropical disturbance is classified as a tropical cyclone when it has 10-minute sustained wind speeds of at least 65 km/h (40 mph) that wrap halfway around the low level circulation centre, while a severe tropical cyclone is classified when the maximum 10-minute sustained wind speeds are greater than 120 km/h (75 mph).
There is a history of tropical cyclones affecting northeastern Australia for over 5000 years; however, Clement Lindley Wragge was the first person to monitor and name them. [2]
In the early history of tropical cyclones in the Australian region, the only evidence of a storm was based on ship reports and observations from land. Later, satellite imagery began in the basin in the 1959-60 season, although it was not continuous until 1970. In Western Australia in particular, the lack of population centers, shipping lanes, radars, and offshore stations meant that storms were tracked infrequently. After the onset of satellite imagery, the Dvorak technique was used to estimate storms' intensities and locations. [3]
Each of three tropical cyclone warning centres (TCWCs) of the Bureau of Meteorology in Perth, Darwin and Brisbane used its own tropical cyclone naming list until the 2008–09 season, when the three TCWCs started to use the single Australian national naming list. From the 2020–21 season, the three TCWCs were unified into one single TCWC which still monitors all tropical cyclones that form within the Australian region, including any within the areas of responsibility of TCWC Jakarta or TCWC Port Moresby. [4] Later in 2021, the Australian tropical cyclone warning centre was officially named as TCWC Melbourne. [5]
The Australian region is currently defined as being between 90°E and 160°E, and is monitored by five different warning centres during the season, which runs from 1 November to 30 April.[ citation needed ]
The Bureau of Meteorology defines four regions within the Australian region which are used when the bureau issues tropical cyclone seasonal outlooks every year. These four regions are named the Western region, the Northwestern sub-region, the Northern region and the Eastern region. The Australian region overall averages eleven tropical cyclones in a season, and the bureau assesses the region as a whole to have a high level of accuracy when forecasting tropical cyclone activity. [6]
The Western region encompasses the area east of 90°E and west of 125°E. [6] The region covers the eastern Indian Ocean including the Cocos (Keeling) Islands and Christmas Island, and waters off Western Australia west of Kuri Bay. The region also covers waters off Indonesia that include the main islands of Java, Bali, Lombok, Sumbawa, Sumba, Flores and the western half of Timor. The region averages seven tropical cyclones in a season, and the bureau assesses the region to have a low level of accuracy when forecasting tropical cyclone activity. [6]
The Northwestern sub-region encompasses the area east of 105°E, west of 130°E and north of 25°S. [6] The sub-region covers waters off Western Australia north of Shark Bay, and extends westward to Christmas Island. The sub-region also covers waters off Indonesia as far west as Java and as far east as Timor. The sub-region averages five tropical cyclones in a season, and the bureau assesses the sub-region to have a moderate level of accuracy when forecasting tropical cyclone activity. [6]
The Northern region encompasses the area east of 125°E and west of 142.5°E. [6] The region covers the Timor Sea, the Banda Sea, the Arafura Sea and the Gulf of Carpentaria. The region averages three tropical cyclones in a season, and the bureau assesses the region to have a very low level of accuracy when forecasting tropical cyclone activity. [6]
The Eastern region encompasses the area east of 142.5°E and west of 160°E. [6] The region covers waters east of Torres Strait and includes the Coral Sea and the Tasman Sea. Lord Howe Island lies within the region, but Norfolk Island lies east of the region, although the bureau continues to monitor tropical cyclones when they are a threat to the external territory. [7] The region also covers waters off Papua New Guinea and western parts of the Solomon Islands. The region averages four tropical cyclones in a season, and the bureau assesses the region to have a low level of accuracy when forecasting tropical cyclone activity. [6]
25 50 75 100 125 150 Jan Feb Mar Apr May Jun Jul Aug Sep Oct Nov Dec
|
| Season | TL | TC | STC | Strongest storm | Deaths | Damage | Retired names | References |
|---|---|---|---|---|---|---|---|---|
| 1960–61 | ||||||||
| 1961–62 | ||||||||
| 1962–63 | ||||||||
| 1963–64 | 2 Audrey | |||||||
| 1964–65 | 3 Flora | |||||||
| 1965–66 | ||||||||
| 1966–67 | 4 Dinah | |||||||
| 1967–68 | ||||||||
| 1968–69 | 15 | 13 | 1 | 3 Amber | ||||
| 1969–70 | 14 | 14 | 1 | 3 Ada | 14 | ? | 3 Ada |
| Season | TL | TC | STC | Strongest storm | Deaths | Damage | Retired names | References |
|---|---|---|---|---|---|---|---|---|
| 1970–71 | 20 | 20 | 10 | 5 Sheila-Sophie | Unknown | ? | 1 Dora 3 Fiona-Gertie | |
| 1971–72 | 18 | 18 | 10 | 4 Emily | Unknown | ? | 4 Althea 3 Daisy 4 Emily | |
| 1972–73 | 15 | 15 | 8 | 3 "Flores" | >1,574 | ? | 4 Madge | [8] |
| 1973–74 | 19 | 19 | 9 | 3 Jessie | Unknown | ? | 2 Wanda | |
| 1974–75 | 16 | 16 | 7 | 5 Trixie | >71 | ? | 4 Tracy 5 Trixie | |
| 1975–76 | 16 | 15 | 8 | 5 Joan | Unknown | ? | 5 Joan 3 David 3 Beth | |
| 1976–77 | 13 | 13 | 6 | 4 Ted | Unknown | ? | 4 Ted | |
| 1977–78 | 9 | 5 | 2 | 5 Alby | Unknown | ? | 5 Alby | |
| 1978–79 | 13 | 12 | 5 | 4 Hazel | Unknown | ? | ||
| 1979–80 | 15 | 15 | 9 | 5 Amy | Unknown | ? | 4 Simon |
| Season | TL | TC | STC | Strongest storm | Deaths | Damage | Retired Names | References |
|---|---|---|---|---|---|---|---|---|
| 1980–81 | 14 | 14 | 11 | 5 Mabel | Unknown | Unknown | 3 Cliff | |
| 1981–82 | 15 | 15 | 7 | 4 Chris-Damia | Unknown | Unknown | ||
| 1982–83 | 7 | 7 | 5 | 5 Elinor | Unknown | Unknown | 4 Jane 4 Elinor | |
| 1983–84 | 22 | 21 | 11 | 5 Kathy | 1 | $19 million | 5 Kathy 2 Lance | |
| 1984–85 | 20 | 18 | 11 | 5 Kristy | 0 | $3.5 million | 3 Nigel 4 Sandy 3 Margot | |
| 1985–86 | 17 | 16 | 8 | 4 Victor | 153 | $250 million | 3 Winifred 3 Manu | |
| 1986–87 | 9 | 7 | 2 | 4 Elsie | 0 | None | 3 Connie 2 Jason 4 Elsie | |
| 1987–88 | 6 | 5 | 2 | 4 Gwenda-Ezenina | 1 | $17.9 million | 2 Agi 2 Charlie 1 Herbie | |
| 1988–89 | 14 | 13 | 6 | 5 Orson | 6 | $93.9 million | 3 Ilona 2 Delilah 4 Ned 5 Aivu 5 Orson | |
| 1989–90 | 14 | 14 | 4 | 5 Alex | Unknown | Unknown | 2 Pedro 3 Felicity 2 Tina 4 Ivor |
| Season | TL | TC | STC | Strongest storm | Deaths | Damage | Retired names | References |
|---|---|---|---|---|---|---|---|---|
| 1990–91 | 12 | 10 | 7 | 4 Marian | 27 | 4 Joy 2 Daphne 2 Fifi | ||
| 1991–92 | 12 | 10 | 9 | 5 Graham | 5 | $9.4 million | 2 Mark 4 Ian | |
| 1992–93 | 8 | 8 | 4 | 4 Oliver | 0 | $950 million | 4 Nina 2 Lena 4 Oliver 2 Roger 3 Adel | |
| 1993–94 | 14 | 12 | 7 | 5 Theodore | 22 | 3 Naomi 3 Pearl 3 Quenton 5 Theodore 4 Sharon | ||
| 1994–95 | 19 | 6 | 6 | 5 Chloe | 1 | 4 Annette 4 Bobby 3 Violet 3 Warren 5 Chloe 4 Agnes | ||
| 1995–96 | 19 | 15 | 9 | 4 Olivia | 1 | $58.5 million | 4 Frank 3 Gertie 4 Barry 3 Celeste 2 Ethel 4 Kirsty 4 Olivia | |
| 1996–97 | 17 | 15 | 5 | 4 Pancho | 34 | $190 million | 1 Lindsay 3 Fergus 3 Rachel 3 Justin 4 Rhonda | |
| 1997–98 | 11 | 9 | 4 | 4 Tiffany | 1 Sid 4 Katrina | [9] | ||
| 1998–99 | 21 | 14 | 9 | 5 Gwenda | 8 | $250 million | 5 Thelma 3 Rona 5 Vance 4 Elaine 5 Gwenda | [9] |
| 1999-00 | 14 | 12 | 5 | 5 Paul | 0 | $251 million | 5 John 2 Steve 3 Tessi 5 Rosita | [9] |
| 147 | 111 | 65 | Gwenda | 98 | ≥$1.71 billion | |||
| Season | TL | TC | STC | Strongest storm | Deaths | Damage | Retired names | References |
|---|---|---|---|---|---|---|---|---|
| 2000–01 | 14 | 8 | 3 | 5 Sam | 2 | $12.8 million | 5 Sam 3 Abigail | [9] |
| 2001–02 | 14 | 10 | 3 | 5 Chris | 19 | $929,000 | 1 Upia 5 Chris | [9] |
| 2002–03 | 11 | 9 | 3 | 5 Inigo | 62 | $28 million | 5 Erica 1 Graham 5 Inigo 1 Epi | [9] |
| 2003–04 | 13 | 10 | 5 | 5 Fay | 0 | $20 million | 4 Monty 5 Fay | [9] |
| 2004–05 | 13 | 10 | 5 | 5 Ingrid | 5 | $14.4 million | 3 Harvey 5 Ingrid | [9] |
| 2005–06 | 18 | 12 | 8 | 5 Monica | 0 | $5.1 million | 3 Clare 4 Larry 5 Glenda 5 Monica | [9] |
| 2006–07 | 8 | 5 | 3 | 5 George | 3 | 5 George | [9] | |
| 2007–08 | 14 | 10 | 3 | 4 Pancho | 149 | $86 million | 3 Guba 2 Helen 2 Durga | [9] |
| 2008–09 | 24 | 10 | 3 | 5 Hamish | 5 | $103 million | 1 Dominic 5 Hamish | [9] |
| 2009–10 | 13 | 8 | 4 | 5 Laurence | 3 | $681 million | 5 Laurence 3 Magda | [9] |
| 137 | 93 | 41 | Inigo | 249 | ≥$1.75 billion | |||
| Season | TL | TC | STC | Strongest storm | Deaths | Damage | Retired names | References |
|---|---|---|---|---|---|---|---|---|
| 2010–11 | 28 | 11 | 6 | 5 Yasi | 3 | $3.56 billion | 1 Tasha 3 Carlos | [9] [10] |
| 2011–12 | 21 | 7 | 3 | 3 Lua | 16 | > $230 million | 3 Heidi 4 Jasmine 3 Lua | [10] |
| 2012–13 | 16 | 9 | 6 | 4 Narelle | 20 | $2.5 billion | 1 Oswald 4 Rusty | [11] |
| 2013–14 | 17 | 10 | 5 | 5 Ita | 22 | $958 million | 3 Christine 5 Ita | |
| 2014–15 | 18 | 9 | 7 | 5 Marcia | 1 | > $732 million | 4 Lam 5 Marcia 3 Olwyn 4 Quang | |
| 2015–16 | 11 | 3 | 0 | 2 Stan | 0 | None | None | [A 1] |
| 2016–17 | 30 | 9 | 3 | 5 Ernie | 16 | $1.8 billion | 4 Debbie | |
| 2017–18 | 23 | 11 | 3 | 5 Marcus | 41 | $165 million | 5 Marcus | |
| 2018–19 | 25 | 11 | 5 | 5 Veronica | 14 | $1.63 billion | 4 Trevor 5 Veronica | |
| 2019–20 | 19 | 9 | 3 | 4 Ferdinand | 28 | $4.3 million | 3 Damien 1 Harold 1 Mangga | |
| 207 | 89 | 38 | Marcus | 161 | ≥$12.6 billion | |||
| Season | TL | TC | STC | Strongest storm | Deaths | Damage | Retired names | Notes |
|---|---|---|---|---|---|---|---|---|
| 2020–21 | 27 | 8 | 3 | 5 Niran | 272 | $518.7 million | 3 Seroja | Second-deadliest Australian region cyclone season on record. |
| 2021–22 | 32 | 10 | 2 | 4 Vernon | 4 | $75 million | 2 Seth | |
| 2022–23 | 25 | 7 | 5 | 5 Darian 5 Ilsa | 8 | $2.7 million | 5 Freddy 3 Gabrielle 5 Ilsa | |
| 2023–24 | 6 | 4 | 3 | 4 Jasper | 1 | $675 million | ||
| Totals | 87 | 27 | 12 | Darian and Ilsa | 285 | $1.27 billion | 2 names |
A Regional Specialized Meteorological Centre (RSMC) is responsible for the distribution of information, advisories, and warnings regarding the specific program they have a part of, agreed by consensus at the World Meteorological Organization as part of the World Weather Watch.
The 1997–98 Australian region cyclone season was a slightly below average tropical cyclone season. It ran from 1 November 1997 to 30 April 1998. The regional tropical cyclone operational plan also defines a tropical cyclone year separately from a tropical cyclone season, and the "tropical cyclone year" ran from 1 July 1997 to 30 June 1998.
The 2008–09 Australian region cyclone season was a near average tropical cyclone season. It officially started on 1 November 2008, and officially ended on 30 April 2009. This season was also the first time that the BoM implemented a "tropical cyclone year." The regional tropical cyclone operational plan defines a "tropical cyclone year" separately from a "tropical cyclone season"; the "tropical cyclone year" began on 1 July 2008 and ended on 30 June 2009.
The 1996–97 Australian region cyclone season was an above average tropical cyclone season. It ran from 1 November 1996 to 30 April 1997. The regional tropical cyclone operational plan also defines a tropical cyclone year separately from a tropical cyclone season, and the "tropical cyclone year" ran from 1 July 1996 to 30 June 1997.
The following outline is provided as an overview of and topical guide to tropical cyclones:
The 2009–10 Australian region cyclone season was a below average tropical cyclone season, with eight tropical cyclones forming compared to an average of 12. The season began on 1 November 2009 and ran through until it end on 30 April 2010. The Australian region is defined as being to south of the equator, between the 90th meridian east and 160th meridian east. Tropical cyclones in this area are monitored by five Tropical Cyclone Warning Centres (TCWC's): Jakarta, Port Moresby, Perth, Darwin, and Brisbane, each of which have the power to name a tropical cyclone. The TCWC's in Perth, Darwin, and Brisbane are run by the Australian Bureau of Meteorology, who designate significant tropical lows with a number and the U suffix. The Joint Typhoon Warning Center also issues unofficial warnings for the region, designating significant tropical cyclones with the "S" suffix when they form west of 135°E, and the "P" suffix when they form east of 135°E.
The 2010–11 Australian region cyclone season was a near average tropical cyclone season, with eleven tropical cyclones forming compared to an average of 12. The season was also the costliest recorded in the Australian region basin, with a total of $3.62 billion in damages, mostly from the destructive Cyclone Yasi. The season began on 1 November 2010 and ended on 30 April 2011, although the first tropical cyclone formed on 28 October. The Australian region is defined as being to the south of the equator, between the 90th meridian east and 160th meridian east. Tropical cyclones in this area are monitored by five Tropical Cyclone Warning Centres (TCWC's): Jakarta, Port Moresby, Perth, Darwin, and Brisbane, each of which have the power to name a tropical cyclone. The TCWC's in Perth, Darwin, and Brisbane are run by the Bureau of Meteorology, who designate significant tropical lows with a number and the U suffix. The Joint Typhoon Warning Center also issues unofficial warnings for the region, designating significant tropical cyclones with the "S" suffix when they form west of 135°E, and the "P" suffix when they form east of 135°E.
The 2011–12 Australian region cyclone season was a below average tropical cyclone season, with 7 cyclones forming rather than the usual 11. It began on 1 November 2011, and ended on 14 May 2012. The regional tropical cyclone operational plan defines a "tropical cyclone year" separately from a "tropical cyclone season"; the "tropical cyclone year" began on 1 July 2011 and ended on 30 June 2012.
The 1993–94 Australian region cyclone season was a slightly above average Australian cyclone season. It was also an event in the ongoing cycle of tropical cyclone formation. It ran from 1 November 1993 to 30 April 1994. The regional tropical cyclone operational plan also defines a tropical cyclone year separately from a tropical cyclone season, and the "tropical cyclone year" ran from 1 July 1993 to 30 June 1994.
The 1990–91 South Pacific cyclone season was a below-average season; only two tropical cyclones occurred within the South Pacific to the east of 160°E. The season officially ran from November 1, 1990, to April 30, 1991, but the first disturbance of the season formed on November 23 and the last dissipated on May 19. This is the period of the year when most tropical cyclones form within the South Pacific Ocean. During the season, no one was killed from tropical disturbances within the South Pacific. However, six people were killed by Cyclone Joy when it made landfall on Australia. The only tropical cyclone to cause any damage while within this basin was Sina, which caused at least $18.5 million (1991 USD) worth of damage to Fiji and Tonga. As a result of the impacts of both Joy and Sina, the names were retired from the tropical cyclone naming lists.
The 2012–13 Australian region cyclone season was a slightly below average tropical cyclone season event in the ongoing cycle of tropical cyclone formation. It officially started on 1 November 2012, and officially ended on 30 April 2013, despite Cyclone Zane being an active system at the time. The regional tropical cyclone operational plan defines a "tropical cyclone year" separately from a "tropical cyclone season"; the "tropical cyclone year" began on 1 July 2012 and ended on 30 June 2013.
The 2013–14 Australian region cyclone season was a slightly below-average tropical cyclone season, with 10 tropical cyclones occurring within the Australian region. It officially started on 1 November 2013, and ended on 30 April 2014. The regional tropical cyclone operational plan defines a "tropical cyclone year" separately from a "tropical cyclone season"; the "tropical cyclone year" began on 1 July 2013 and ended on 30 June 2014.
The 2014–15 Australian region cyclone season was a slightly below average tropical cyclone season, though it featured numerous intense cyclones. The season officially ran from 1 November 2014, to 30 April 2015, however, a tropical cyclone could form at any time between 1 July 2014, and 30 June 2015, and would count towards the season total. During the season, tropical cyclones were officially monitored, by one of the five Tropical Cyclone Warning Centres (TCWCs) that are operated in this region.
The 2015–16 Australian region cyclone season was the least active Australian region cyclone season since reliable records started during 1969, with only three named tropical cyclones developing in the region. Reasons for the low activity during the year included a positive Indian Ocean Dipole occurring and the 2014–16 El Niño event. Ahead of the season starting; the Australian Bureau of Meteorology predicted that there was a 91% chance that the season would be below average. As the 2015–16 tropical cyclone year opened on 1 July 2015, the newly named Tropical Cyclone Raquel moved south-westward into the Australian region. Over the next couple of days, the system meandered around 160°E and moved through the Solomon Islands, before it was last noted on 5 July. The basin subsequently remained quiet with only several weak tropical lows developing, before the first named tropical cyclone of the season was named Stan during 29 January 2016.
The 2016–17 Australian region cyclone season, despite a very high number of tropical lows, was a slightly below-average season in terms of activity, with nine tropical cyclones, three of which intensified further into severe tropical cyclones; though it was much more active than the previous season. The season was the first to have a severe tropical cyclone since the 2014–15 season. It was the period of the year when most tropical cyclones form in the Southern Indian Ocean and Pacific Oceans between 90°E and 160°E. The season officially ran from 1 November 2016 to 30 April 2017, however, a tropical cyclone could form at any time between 1 July 2016 and 30 June 2017 and would count towards the season total. The first named storm, Yvette, developed during 21 December, and the final named storm, Greg, left the region on 3 May as a remnant low. This season was also the second-costliest tropical cyclone season on record in the Australian region basin, behind only the 2010–11 season, with a total of AUD$3.7 billion in damages incurred by the various storms, mostly from Cyclone Debbie.
The 2017–18 Australian region cyclone season was an average period of tropical cyclone formation in the Southern Indian Ocean and South Pacific Ocean, between 90°E and 160°E, with 11 named storms, which 3 intensified into severe tropical cyclones. Another two tropical cyclones, Cempaka and Flamboyan occurred outside the Australian region but are included in the descriptions below. The season officially began 1 November 2017 and ended on 30 April 2018; however, tropical cyclones can form at any time of the year, as demonstrated by the first tropical low of the season in early August. Any tropical system that forms between 1 July 2017 and 30 June 2018 will count towards the season total. During the season, tropical cyclones will be officially monitored by one of the five tropical cyclone warning centres (TCWCs) that operate in this region. Three of the five centres are operated by the Australian Bureau of Meteorology (BOM) in Perth, Darwin and Brisbane, while the other two are operated by the National Weather Service of Papua New Guinea in Port Moresby and the Indonesian Agency for Meteorology, Climatology and Geophysics in Jakarta. The Joint Typhoon Warning Center (JTWC) of the United States and other national meteorological services, including Météo-France at Réunion, also monitored the basin during the season.
The 2018–19 Australian region cyclone season was an average season that saw the formation of 11 tropical cyclones, six of which intensified further to become severe tropical cyclones. The season officially began on 1 November 2018 and concluded on 30 April 2019; however, as evidenced by Tropical Low Liua in September 2018 and Tropical Cyclones Lili and Ann in May 2019, tropical cyclones can form at any time of the year. As such, any system existing between 1 July 2018 and 30 June 2019 would count towards the season total. During the season, tropical cyclones were officially monitored by the Bureau of Meteorology (BOM), the Indonesian Agency for Meteorology, Climatology and Geophysics (BMKG) in Jakarta, Indonesia, and the National Weather Service of Papua New Guinea in Port Moresby. The United States' Joint Typhoon Warning Center (JTWC) in Hawaii, and other national meteorological services such as MetService in New Zealand, Météo-France at La Réunion, and the Fiji Meteorological Service (FMS), also monitored parts of the basin during the season in an unofficial capacity.
The 2019–20 Australian region cyclone season was a below average tropical cyclone season for the waters surrounding Australia between longitudes 90°E and 160°E. The season officially began on 1 November 2019 and ended on 30 April 2020; however, tropical cyclones can form at any time of year, as evidenced by Tropical Cyclone Mangga during May 2020. As such, any system existing between 1 July 2019 and 30 June 2020 would count towards the season total. The season featured the region's second-latest start on record, with the formation of the first tropical low only occurring on 4 January 2020. A total of eight tropical cyclones formed during the season, which represents the region's least active season since the 2016–17 season. Three systems intensified further into severe tropical cyclones, and three systems made landfall within the region at tropical cyclone intensity. A total of 28 fatalities were caused, either directly or indirectly, as a result of impacts from the season's systems. Cyclone Ferdinand was the strongest of the season reaching Category 4 in late February 2020. However, it was the second-strongest storm, Cyclone Damien, that was the most damaging. Damien was the strongest tropical cyclone to strike Western Australia's Pilbara Region since Cyclone Christine in 2013, making landfall directly over the town of Dampier.
The 2020–21 Australian region cyclone season was a below average but very deadly season when most tropical cyclones formed in the Southern Indian Ocean and Pacific Oceans between 90°E and 160°E. It produced 8 tropical cyclones with 3 strengthening into severe tropical cyclones. However, it featured the region's third-deadliest cyclone on record—Cyclone Seroja, which brought severe floods and landslides to southern Indonesia and East Timor. The season officially began on 1 November 2020 and started with the formation of Tropical Low 01U on 24 November within the basin, which would later become Tropical Storm Bongoyo in the South-West Indian Ocean, and ended with the dissipation of a tropical low on 24 April, 6 days before the season ended on 30 April. However, a tropical cyclone could form at any time between 1 July 2020 and 30 June 2021 and would count towards the season total. During the season, tropical cyclones were officially monitored by one of the three tropical cyclone warning centres (TCWCs) for the region which are operated by the Australian Bureau of Meteorology, National Weather Service of Papua New Guinea and the Indonesian Agency for Meteorology, Climatology and Geophysics. The United States Joint Typhoon Warning Center (JTWC) and other national meteorological services including Météo-France also monitored the basin during the season.
The 2016–17 South Pacific cyclone season was the least active South Pacific cyclone season since the 2011–12 season, with only four tropical cyclones occurring within the South Pacific Ocean to the east of 160°E. Two of the four systems developed into severe tropical cyclones on the Australian tropical cyclone intensity scale. The season officially ran from November 1, 2016 until April 30, 2017. However, May featured two post-season systems: Donna and Ella, of which the former was the strongest post-season South Pacific tropical cyclone ever recorded in that month. Overall, 22 tropical disturbances were monitored by a combination of the Fiji Meteorological Service (FMS), Australian Bureau of Meteorology (BoM) and New Zealand's MetService.
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