Severe Tropical Cyclone Seroja
Category 3 severe tropical cyclone (Aus scale)
Category 1 tropical cyclone (SSHWS)
Seroja 2021-04-11 0605Z.jpg
Seroja approaching the Mid West region of Western Australia on 11 April
Formed3 April 2021
Dissipated12 April 2021
(Extratropical after 12 April)
Highest winds10-minute sustained: 120 km/h (75 mph)
1-minute sustained: 130 km/h (80 mph)
Lowest pressure971 hPa (mbar); 28.67 inHg
Fatalities223 total, 102 missing
(Third-deadliest Australian region tropical cyclone on record)
Damage> $100 million (2021 USD)
Areas affectedIndonesia, East Timor, Western Australia
Part of the 2020–21 Australian region cyclone season

Severe Tropical Cyclone Seroja was a deadly tropical cyclone that brought historic flooding and landslides to portions of southern Indonesia and East Timor and later went on to impact Western Australia's Mid West region, becoming one of the first to do so since Cyclone Elaine in 1999. The twenty-second tropical low, seventh tropical cyclone, and third severe tropical cyclone of the 2020–21 Australian region cyclone season, the precursor of Seroja formed off the south coast of Timor island as Tropical Low 22U at 18:00 UTC on 3 April 2021. The tropical low moved very slowly near the island, while the system's thunderstorms increased in organization. The low intensified into Tropical Cyclone Seroja by 4 April, while it was passing north of Rote Island, while continuing its slow strengthening trend.

Due to the presence of Tropical Cyclone Odette in Seroja's vicinity, interaction was anticipated as the storm moved away from Indonesia and East Timor. Its intensity fluctuated as it moved southwest, with its strengthening being highly hindered due to interaction with Odette. This caused the system to weaken as Seroja moved closer to it, due to a phenomenon known as the Fujiwhara effect. Eventually, Seroja began to restrengthen and weaken Odette, with Seroja absorbing Odette into its circulation on 10 April. Due to Odette, Seroja was steered to the southeast towards Australia, before strengthening even further. At around 8 p.m. local time on 11 April, Seroja made landfall on the western coastline of Western Australia as a Category 3 severe tropical cyclone, slightly south of the coastal town of Kalbarri, bringing heavy rain and hurricane-force wind gusts (about 170 km/h, or 110 mph). Later that day, Seroja began accelerating southeastward while weakening. On 12 April, Seroja emerged off the southern coast of Western Australia while beginning to undergo an extratropical transition, before being absorbed into another larger extratropical cyclone to the south. The name Seroja means lotus in Indonesian.[1]

As of 13 April 2021, it is estimated that at least 223 people were killed by the storm, with 180 people in Indonesia, 42 in East Timor,[2][3][4] and one in Australia.[5][6] At least 72 people from Indonesia and 30 from East Timor are still missing.[7][8] The cyclone damaged or destroyed at least 90 houses and five bridges in Indonesia's East Nusa Tenggara province while 2,655 people were evacuated to government-owned shelters.[9][10] Around 9,000 people were displaced on East Timor, while at least 10,000 homes have been submerged.[11][12][7] Damage reports from Kalbarri, Western Australia started coming in soon after the storm made landfall.

Meteorological history

Map plotting the track and the intensity of the storm, according to the Saffir–Simpson scale

On 29 March, the BoM began to mention that Tropical Low 22U was developing to the south of Timor. By 3 April, the tropical low fully developed as it was within an active trough.[13] The low was located in a generally favorable environment with deep moisture, low vertical wind shear, and defined outflow.[14] The low drifted close to the coast of Timor very slowly with persistent spiraling bands of convection occupying the storm's circulation, producing prolific rainfall in the surrounding regions on 3–4 April.[15] At this time, the low pressure system was located inside the Area of Responsibility (AoR) of TCWC Jakarta.[16] By the early morning of 4 April, the presentation of its structure had improved with spiral bands of deep convection and tight curvature at its center.[17] Although there were fluctuations in central convection, a favorable environment of deep moisture, low vertical wind shear, and good outflow meant further development of the system was expected.[14][15] Meanwhile, the Joint Typhoon Warning Center (JTWC) issued their first warning on the storm as Tropical Cyclone 26S at 15:00 on UTC 4 April.[18] The tropical low slowly gained strength, intensifying to a Category 1 tropical cyclone, and was given the name Seroja by the Tropical Cyclone Warning Centre (TCWC) Jakarta at 20:00 UTC on 4 April, about 95 km (60 mi) north-northwest of Rote Island.[19][20]

Tropical Cyclone Odette (left) and Tropical Cyclone Seroja (right) engaging into a Fujiwhara interaction while intensifying between 7–9 April.

During 5 April, Seroja continued to move at 3 km/h (1.9 mph) in a west-southwest direction, away from the Indonesian coastline. The storm intensified to a Category 2 tropical cyclone at 19:00 UTC, with 10-minute sustained winds of 105 km/h (65 mph) and its central pressure deepening to 982 mb (29.00 inHg).[21] Long term uncertainty in both track and intensity persisted in the forecasting of Seroja's track, due to interaction with Tropical Low 23U, to the far west of the storm.[21] Seroja held this strength for roughly 12 hours, before unexpectedly weakening to a Category 1 tropical cyclone yet again on 6 April, due to southeasterly wind shear, and dry air partially exposing the low level circulation (LLC) and degrading its thunderstorm activity.[22] Seroja fluctuated in strength for several hours, intensifying slightly on 7 April, as it continued in a generally southwesterly direction.[23] Seroja became disorganized on satellite imagery as convection became dislocated to the south on 8 April, while it began to closely interact with Tropical Cyclone Odette (formerly Tropical Low 23U) just to the northwest, as a result of the Fujiwhara effect, complicating the forecasts for the tropical cyclone and causing it to weaken again.[24] Seroja resumed intensification by the next day, re-intensifying into a Category 2 tropical cyclone at 13:16 UTC on 9 April, as the storm began to absorb Odette and as wind shear started to ease off.[25] By 10 April, Seroja had absorbed most of Odette's remaining thunderstorms and began to accelerate to the southeast towards Western Australia, maintaining a relatively organized structure.[26] Later that day, Seroja fully absorbed Odette into its circulation.

Seroja continued to steadily intensify as it approached the Gascoyne Region; the JTWC upgraded Seroja to a Category 1–equivalent tropical cyclone on the Saffir–Simpson scale, with sustained winds of 120 km/h (75 mph), at 18:00 UTC on 10 April.[27] By early on 11 April, Seroja had intensified into a Category 3 severe tropical cyclone, the third severe tropical cyclone of the season, as a ragged eye began to emerge from the cyclone's central dense overcast.[28] Seroja continued rapidly accelerating to the southeast at 53 km/h (32 mph), with its eye becoming more defined on infrared and Doppler radar images before making landfall near Gregory, Western Australia, or just north of Geraldton at peak strength with 1-minute sustained winds of 130 km/h (80 mph), 10-minute sustained winds of 120 km/h (75 mph), and a minimum central pressure of 971 hPa (28.76 inHg), with observations of gusts as high as 150 km/h (90 mph).[29][30] Following landfall, Seroja quickly moved to the southeast over Australia, while gradually weakening. Early on 12 April, Seroja's extratropical remnant entered the Great Australian Bight, while beginning to transition into an extratropical cyclone, before being absorbed into a larger extratropical cyclone to the south later that day.



The Meteorology, Climatology, and Geophysical Agency of the Indonesian government declared two days before the cyclone's formation that they were already anticipating the possibility of tropical cyclone development over the Savu Sea.[31] On 4 April 2021, the agency issued an early warning.[32][33] On 8 April 2021, the agency again issued warnings to other provinces such as Bali, East Java, Central Java, and West Nusa Tenggara.[34]


The Australian Bureau of Meteorology (BOM) warned on 5 April 2021 that Seroja could approach the West Pilbara or Gascoyne coastline. It was also advised that tourists be ready to change plans, in case the cyclone impacts the area and brings unsafe conditions to go home.[35][36] Due to the cyclone's uncertain track from its Fujiwhara interaction with Tropical Cyclone Odette, the chance of impacts on Western Australia was uncertain as to where it would go; out to sea or into land.[37] As the storm approached Australia, the price of Australian commodities such as coals and iron ores were expected to rise. In addition, there was concern that it would disrupt or delay shipments and trades from the region.[38] The BOM also issued a tropical cyclone watch early on 9 April for much of the region between Coral Bay and Lancelin.[39]

Department of Fire and Emergency Services (DFES) Acting Commissioner Craig Waters advised all people in the watch area to 'leave immediately' as many of the homes in the area would be under significant risk with pre-saturated soil allowing flooding to likely occur much more easily.[40] BOM also mentioned that this region was not accustomed to tropical cyclone impacts, making the risk of Seroja's impacts more dangerous than usual with a month's worth of rain expected to fall within a day.[41][42] A tropical cyclone warning was then issued for Cape Cuvier to Geraldton on 10 April as Seroja neared, albeit strengthening slower than anticipated. All people between Coral Bay and Geraldton were eventually told to evacuate immediately on 11 April as homes were not built to withstand such high winds.[43]

Premier Mark McGowan said that Seroja was "like nothing we have seen before in decades". There was a Red Alert placed along an 800 kilometer stretch of coastline south of Carnarvon and Lancelin. The people under the alert were required to stay in their houses or in an evacuation center. The latter structures were open in Port Denison, Carnarvon and Denham. The cyclone was expected to impact the area until midnight. High tides, intense rainfall, flash flooding, dangerous surf and beach erosion were among the warned dangers of Seroja.[44]


Flooding and soil liquefaction in the capital of East Timor, Dili
Aftermath of flood caused by the cyclone, East Flores Regency

East Timor

In East Timor, a landslide and floods displaced more than 8,000 people and led to the deaths of 42 people in total.[45][46][47][48][49][7][4] The storm caused power outages in the entirety of East Timor, in addition to damaging the presidential palace.[49] Flood caused by the storm damaged national laboratory of Guido Valadares National Hospital, the only laboratorium in the country, causing concern that it would affect East Timor's effort to mitigate the COVID-19 pandemic.[50] The flood also seemed to have to damaged the country's central pharmacy, where vaccine stocks for East Timor population stored.[50][51] Other damaged facilities include two COVID-19 isolation facilities.[52][52][53][54] It is thought that many more people in East Timor have died due to the storm's widespread flooding.[53][54] At least 30 people remain missing.[47][7]

Preliminary reports from 7 April 2021 showed that approximately 10,325 people were affected by the storm's impact. 76% of those people were in the Dili municipality. The rains were so heavy that the capital was referred to as a "mud pit".[55] Damage from Seroja in East Timor was expected to exceed US$100 million, according to Prime Minister Taur Matan Ruak.[56]


As a tropical low, Seroja caused widespread rainfall and thunderstorms in West Nusa Tenggara and East Nusa Tenggara provinces in Indonesia.[57][58][59] In the early hours of 4 April, floods struck the island, hours before people intended to gather for Easter celebrations. In the immediate aftermath, 41 people were killed and 28 seriously injured.[47] Bridges and roads connecting to Flores Island and Adonara Island were destroyed.[59][60] Two rivers in Ende district burst their banks killing two people and resulted in extensive flooding in East Flores.[47][47] Dozens of homes were buried under mudslides in the village of Lamenele on Adonara island.[59][60][47] In the East Flores Regency, fourteen villages were hit by flash flooding as a result of runoff of volcanic materials from Mount Ile Lewotolok.[47][61]

In the City of Kupang, 734 houses were damaged, affecting 2,190 people, while in Rote Ndao, around 30 houses were flooded.[62][63] A bridge connecting the cities of Kupang and Malaka Regency was destroyed, making travel between the two regions extremely difficult.[64][65] A passenger ship, the Jatra I, sunk on a port in Kupang city, after experiencing a leak. However, no casualties were reported from the sinking.[66][67] Another ship, the Namparnos, went adrift and grounded on Kambing Island.[67] Trans-Timor roads were flooded, cutting off access between regencies.[63] The office building of the governor of East Nusa Tenggara, commonly known as "Sasando Building" was also damaged by the cyclone.[68] In the province, 1,114 houses were reported as damaged or destroyed, up to 72 missing people, and 8,424 displaced.[8]

Five cities and regencies experienced power outages, but electricity was partially restored later.[69] At least 98 base transceiver stations in East Nusa Tenggara province were damaged, although some were restored later by the Ministry of Communication and Information Technology.[70] Four fuel trucks owned by Pertamina were damaged.[71] A dam in East Sumba overflowed, causing a flood in a neighboring city.[72] The cyclone affected areas as far as city of Bima in West Nusa Tenggara, where it caused floods, submerging 10,000 homes and affecting more than 27,000 people.[47][73][74] On Lembata, the rain loosened solidified lava from an eruption in November of Ili Lewotolok volcano. The stone tumbled into several villages, killing at least 11 people.[74]

As of 13 April, the death toll in the country had risen to 180.[2] The high death toll was most likely because most people were sleeping when the cyclone made landfall, meaning that it was unexpected.[75]


Cyclone Seroja making landfall in Western Australia on 11 April

After Seroja made landfall, around 4,350 people in Western Australia lost electricity as the storm's high winds downed power lines, particularly around Kalbarri.[76] A wind gust of 170 kilometres per hour (110 mph) was additionally recorded in Kalbarri while around 100 millimetres (3.9 in) of rain fell within just hours, likely being one of the strongest wind gusts recorded in the city in more than 50 years.[77][78] This number of power outages soon increased to over 25,000 within hours of landfall as Seroja accelerated further inland.[79] Shortly after, unconfirmed reports claimed that buildings had already had their roofs torn off and even entire homes and sheds were completely destroyed.[80] Carnarvon's famous 124-year old "One Mile Jetty" collapsed and floated out to sea.[81] Some residents were required to barricade themselves within bathrooms or cupboards as their homes were damaged.[82] In the daytime, Department of Fire and Emergency Services (DFES) reported around 70% of structures in Kalbarri were damaged, while around 40% of those properties had been completely destroyed.[83][84] The services also received around 175 calls by the morning of 12 April.[83] Businesses based around the tourist industry in Kalbarri were afraid they might never be able to reopen.[85] News reporters reported that some houses had been completely flattened by the cyclone.[85] Heavily damaged structures in Kalbarri left the presence of asbestos fibres on the ground and airborne, which can be deadly when inhaled.[86] Widespread damage was also reported in Northampton.[87] Shire of Northampton President Craig Simkins described the damage as if a "bomb had gone off", many structures having lost their roofs or been severely damaged, leaving Simkins perplexed whether there should be a new building code to accommodate to future cyclones in the region.[88] Recovery was estimated to take several months or even years in the small town.[89] Access and communication to towns further north impacted by the cyclone, such as Geraldton, was cut off, leaving the scale of damage in the city largely unknown.[90] The cyclone was later declared as an 'insurance catastrophe', according to the Insurance Council of Australia.[91][90]

During the cyclone, one person died; a 38-year-old maintenance worker who was electrocuted in Coral Bay after attempting to secure a caravan park’s private power pole which had fallen down in the wind.[5][6] There were no other reports of casualties or severe injuries.[84] Australian Prime Minister Scott Morrison offered federal government support for recovery in Kalbarri.[92] A fundraiser by Lord Mayor's Distress Fund in Western Australia raised AUD$2.75 million (US$2.12 million) in a little over a day to help families impacted by the cyclone.[93] Australian footballer Jamie Cripps reportedly lost his family home which was destroyed in Northampton due to Seroja.[94]


East Timor

East Timor Prime Minister Taur Matan Ruak cited the floods as one of the most devastating incidents to affect the country in 40 years.[45] The East Timor government later held an emergency meeting to assess the situation.[50] The Civil Protection Agency of Timor Leste is currently planning an emergency response. According to the Lusa News Agency, it is impossible for East Timor to currently balance the damage mitigation with the limited resources the country has.[95][52] Portugal was ready to send assistance to East Timor, according to Foreign Minister Augusto Santos Silva.[52] The European Union and United Nations also expressed sympathy and said that they are ready to assist the East Timor government to repair damaged infrastructure and provide assistance for victims.[52] The East Timorese Minister of Interior distributed foods to victims in a hotel, which he said to have been cooked by his wife.[46] TSF Radio said the assistance was symbolic and far from enough to assist the victims.[46] Local churches in Dili mobilizes priests & pastors to voluntarily help the victims.[7] Government of East Timor reintroduced COVID-19 lockdown on three cities; Dili, Baucau, and Viqueque amid rising infection case after the disaster until 2 May.[7] Transmission of other waterborne diseases such as cholera, dengue fever, and malaria was also expected to quickly rise due to the immense floods.[56] United Nations developmental coordinator Alex Tilman said East Timor would not have the necessary resources alone to recover from the cyclone.[56] The first COVID-19 death recorded in the country occurred shortly after the cyclone.[96][56] Prime Minister of Australia Scott Morrison promised additional COVID-19 vaccine doses would be diverted to East Timor.[56] In addition, a state of emergency was declared to speed up mitigation process.[4]

Leader of Fretilin, Mari Alkatiri urged East Timor government to ask for more international assistance such as helicopter and military cargo.[4] He said he already met with United Nations ambassador on Dili to discuss about more assistance.[4]


Several schools on the Indonesia-Timor Leste border were evacuated by the Indonesian Army stationed there before they collapsed.[97][98] Police in Kefamenanu assisted by the army evacuated most of the town residents amid flooding in the region.[99] Evacuation processes in the East Flores Regency was hampered by the lack of heavy equipment, limited access to the sea, and a lack of effective shelter in the area.[60][100] The Indonesian electricity company PLN was only able to repair 82% of damaged power infrastructure in residential areas, while the rest was difficult to repair because of the extreme weather and floods.[101][102]

The City of Kupang declared a state of emergency, but they lacked emergency response funds and had limited personnel to provide a response.[63] An emergency bridge was constructed to help victims evacuate in East Flores.[103] Indonesian President Joko Widodo at a press conference on 5 April 2021, offered his condolences "in the name of all Indonesian people".[104][105] He also urged all government institutions to mitigate the damage caused by the cyclone.[106] In addition, the Nasdem Party set up public kitchens for the victims.[107] The chief of the Indonesian National Board for Disaster Management (BNPB), Doni Monardo planned to visit the affected regions on 5 April 2021.[108][109] After the visit, he concluded that health infrastructures & facilities in most of East Nusa Tenggara are adequate, but lack of health workers & doctors.[110] Later president also held a brief meeting to address the disaster.[111]

Seroja moving away from Indonesia on 5 April

In addition to rubber boats, shelters, and personnel, the Indonesian government sent food, blankets, masks, and COVID-19 rapid tests.[112][113][114] Pertamina responded by replacing 4 damaged fuel trucks, which would be used to help distribute fuel to victims in the region.[115] As of 5 April 11:00 a.m. Western Indonesian Time (WIB), a logistical route for fuel to Adonara Island has been restored.[116] El Tari International Airport has resumed its operations on 5 April 10:00 WIB after being closed since the night before.[117] Indonesia's navy readied hospital ships to help treat injured survivors. Helicopters also dropped food and other essentials into remote villages, while sniffer dogs were deployed to search for the dozens missing from the cyclone.[118]

Distribution of aid was limited by the severe weather and damaged infrastructure.[119][120] As the result, the government sent four helicopters and one cargo airplane to assist distribution.[121] The People's Representative Council urged the government to speed up the distribution of relief and suggested using Indonesian army personnel to help overcome logistical hurdles.[113][122] The Ministry of Social Affairs sent aid to flood victims in the city of Bima.[123] Kodam IX/Udayana personnel constructed eight shelter center, 20 field kitchens, and six field hospitals.[124] Hadi Tjahjanto, the Commander of Armed Forces, sent a navy ship known as KRI Oswald Siahaan (354), a Lockheed C-130 Hercules, a helicopter, and several battalions of military engineers from Kodam IX/Udayana and Kodam XIV/Hasanuddin to assist evacuation & reconstruction of infrastructures.[125]

The central government of Indonesia prepared additional state funds to assist victims and the reconstruction of cities and villages in the province.[126] Indonesians organized a donation campaign for victims, especially for East Nusa Tenggara, and gathered almost 1,000,000,000 rupiahs or around $70,000 as of 6 April.[127] Ministry of Social Affairs gave compensation of around $1,000 each for deceased victim and $300 each to injured victims, in addition of other aids totaling around $760,000.[128] Each family of a victim also received 500,000 rupiahs or $35 per month for them to pay rent on family's houses or local homestay, as to minimize amount of shelter camps amid COVID-19 until their house was reconstructed by the government.[129][130] In addition, there's also compensation for each damaged houses; around $3,500 for heavily damaged, $1,500 for moderately damaged, and around $700 for lightly damaged.[131] Governor of East Java, Khofifah Indar Parawansa also send additional assistance & aid to affected region.[132] COVID-19 Task Force personnel were sent to the affected regions & shelters to limit the spread of COVID-19, using experience from 2021 South Kalimantan floods and 2021 West Sulawesi earthquake.[133] Regional Police of the province inspected all of the building material stores in the region to prevent sellers putting high prices for reconstruction.[134][135]

Logistical assistance from Indonesian Ministry of Social Affairs.

As of 6 April, more than 8,400 residents across the province had been evacuated. The majority of those who evacuated (at least 7,000 people) were residents in East Sumba Regency. The BNPB stated that at least 12 administrative regions in East Nusa Tenggara had been affected by the cyclone, of which 8 were severely affected.[136][137] Chinese President Xi Jinping offered his condolences on the disaster.[138] On Friday, president Joko Widodo paid a visit to Adonara island and Lembata Regency.[139][140][141]

Currently, regions affected in Indonesia already moved into rehabilitation and reconstruction process as more missing victims were found and the cyclone is moving away.[142][143][144][145]


The lack of warnings by the government prior to the cyclone and no direct response by the local government was criticized by Indonesian netizens and NGOs, such as WALHI, for worsening the effect of the cyclone.[146] The hashtag #PrayforNTT became viral in Indonesia through Twitter.[147][148] WALHI pressured the provincial government of the province of East Nusa Tenggara to declare a state of emergency and criticized the lack of a response from the governor there, Viktor Laiskodat.[149][17] The Prosperous Justice Party criticized Indonesian president Joko Widodo for attending the marriage of Indonesian celebrity Atta Halilintar instead of addressing the disaster of Seroja.[150][151] The governor of East Nusa Tenggara declared a state of emergency on 6 April 2021, which was thought to be too late by many.[who?][152][153] People in the affected regions asked President Joko Widodo to come instead of asking local officials to assist because they are considered too slow and uncoordinated.[154] A member of the Indonesia National Student Movement from the region harshly criticized the local government and asked the President to directly see and discipline them.[154]

See also