Tropical Cyclones in 2023 > Review of tropical cyclones in 2023

2.1 Review of tropical cyclones in 2023

2.1.1 Tropical cyclones over the western North Pacific (including the South China Sea)

In 2023, a total of 19 tropical cyclones occurred over the western North Pacific (WNP) and the South China Sea (SCS) bounded by the Equator, 45°N, 100°E and 180°, considerably less than the long-term (1961 - 2020) average figure of around 30. During the year, 11 of the tropical cyclones attained typhoon intensity or above, less than the long-term average (1961 - 2020) of about 15, with five of them reaching super typhoon intensity (maximum 10-minute wind speed of 185 km/h or above near the centre).

Figure 2.1 shows the monthly frequencies of the occurrence of tropical cyclones in WNP and SCS in 2023.

During the year, six tropical cyclones made landfall over China, with one of them crossing the coast of southern China within 300 km of Hong Kong and two crossed Taiwan. Two made landfall over the Philippines and one made landfall over Vietnam. With an estimated maximum sustained wind speed of 250 km/h and a minimum sea-level pressure of 900 hPa near the centre (Table 4.1), Super Typhoon Mawar (2302) in May to June (Figure 2.3) was the most intense tropical cyclone over the WNP and the SCS in 2023.

2.1.2 Tropical cyclones in Hong Kong's area of responsibility

Amongst the 19 tropical cyclones in 2023, 10 of them occurred inside Hong Kong's area of responsibility (i.e. the area bounded by 10°N, 30°N, 105°E and 125°E), less than the long-term annual average (1961-2020) figure of around 16 (Table 2.1). Three of them developed within Hong Kong's area of responsibility. Altogether, 314 tropical cyclone warnings to ships and vessels were issued by the Hong Kong Observatory this year (Table 4.2).

2.1.3 Tropical cyclones over the South China Sea

Seven tropical cyclones affected SCS bounded by 10°N, 25°N, 105°E and 120°E in 2023, less than the long-term annual average (1961-2020) of around 12. Two of them formed over the region.

2.1.4 Tropical cyclones affecting Hong Kong

In 2023, the typhoon season in Hong Kong started on 15 July. Tropical Depression Talim (2304) moved towards the northern part of the SCS in that morning, necessitating the issuance of the Standby Signal No. 1. The typhoon season ended with the cancellation of all tropical cyclone warning signals on 9 October when Tropical Depression Koinu (2314) further departed from Hong Kong and weakened in that afternoon.

Five tropical cyclones affected Hong Kong during 2023 (Figure 2.2), slightly less than the long-term (1961-2020) average of about six in a year (Table 2.2). They were Typhoon Talim (2304) and Super Typhoon Doksuri (2305) in July, Super Typhoon Saola (2309) and Severe Typhoon Haikui (2311) in August to September and Severe Typhoon Koinu (2314) in September to October. The No. 10 Hurricane Signal was issued during the passage of Saola on 1 September, the highest tropical cyclone warning signal issued in 2023 and the first No. 10 Hurricane Signal since Mangkhut in 2018. The Increasing Gale or Storm Signal No. 9 and the No. 8 Gale or Storm Signal were issued during the passages of Koinu and Talim respectively. Doksuri and Haikui necessitated the issuance of the Standby Signal No. 1 in Hong Kong.

2.1.5 Tropical cyclone rainfall

Tropical cyclone rainfall for Hong Kong (total rainfall recorded at the Hong Kong Observatory Headquarters from the time when a tropical cyclone comes within 600 km of Hong Kong to 72 hours after it has dissipated or moved more than 600 km away from Hong Kong) in 2023 was 1427.8 mm (Table 4.8.1), which accounted for approximately 51.5% of the year’s total rainfall of 2774.5 mm and more than double of the 1961-2020 long-term average of 704.2 mm.

According to the above definition, Severe Typhoon Haikui (2311) brought 641.1 mm of rainfall to Hong Kong (Table 4.8.1) and was the wettest tropical cyclone in 2023, breaking the previous record of 616.5 mm set by Typhoon Sam in 1999, and making it the wettest tropical cyclone ever to affect Hong Kong since records began in 1884.

2.2 Monthly overview

A monthly overview of tropical cyclones in 2023 is given in this section. Detailed reports on tropical cyclones affecting Hong Kong, including reports of damage, are presented in Section 3.

JANUARY TO MARCH

No tropical cyclone formed over the western North Pacific and the South China Sea from January to March 2023.

APRIL

A tropical depression formed over the western North Pacific about 650 km east of Manila on the morning of 11 April, with an estimated maximum sustained wind of 45 km/h near its centre. It generally tracked westwards and weakened into an area of low pressure over the central part of the Philippines next day.

Sanvu (2301) formed as a tropical depression over the western North Pacific about 1 660 km east-southeast of Guam in the small hours on 20 April. It moved generally northwestwards and intensified gradually. Sanvu intensified into a tropical storm in that afternoon, reaching its peak intensity next morning with an estimated maximum sustained wind of 75 km/h near its centre. Sanvu turned to move westwards and weakened afterwards. It finally dissipated over the western North Pacific on 22 April.

MAY TO JUNE

Mawar (2302) formed as a tropical depression over the western North Pacific about 1 070 km south-southeast of Guam in the small hours on 20 May. It moved north-northwestwards and intensified gradually. Mawar intensified into a super typhoon on the morning of 23 May. After skirting past Guam, it turned to move west-northwestwards towards the seas east of Luzon the next day. Mawar reached its peak intensity with an estimated sustained wind of 250 km/h near the centre in the small hours on 26 May. It weakened gradually afterwards and became a severe typhoon on 28 May. Mawar turned gradually to move northeastwards across the vicinity of Ryukyu Islands and continued to weaken in the following five days. Mawar finally evolved into an extratropical cyclone over the western North Pacific to the south of Japan on 3 June.

According to press reports, Mawar brought torrential rain and squalls, causing devastation in Guam and power outages in most parts of the island. 72-hour rainfall of 714 millimetres were recorded locally.

Guchol (2303) formed as a tropical depression over the western North Pacific about 560 km northwest of Yap in the small hours on 6 June. It moved generally northwestwards and intensified gradually. Guchol intensified into typhoon on the afternoon of 8 June and reached its peak intensity with an estimated sustained wind of 145 km/h near the centre in the small hours on 10 June. It turned to move northeastwards and weakened gradually afterwards. Guchol finally evolved into an extratropical cyclone over the western North Pacific to the south of Japan on 12 June.

JULY TO OCTOBER

Talim (2304) formed as a tropical depression over the central part of the South China Sea about 490 km southeast of Dongsha on the morning of 14 July. It moved westwards at first and intensified gradually. Talim intensified into a tropical storm and entered the northern part of the South China Sea the next day. Talim turned to move west-northwestwards that night and continued to edge towards the coast of western Guangdong. Talim intensified further into a typhoon on the night of 16 July and attained its peak intensity with an estimated maximum sustained wind of 140 km/h near its centre on the morning of 17 July. Talim made landfall near Zhanjiang, Guangdong that night, and moved across Leizhou Peninsula and Beibu Wan the next morning. It moved into inland Guangxi on 18 July and degenerated into an area of low pressure over the northern part of Vietnam the next morning.

According to press reports, two people were injured when Talim affected Macao. There were also 32 incident reports, including five cases of fallen trees and one case of collapsed scaffoldings. Besides, Talim also brought torrential rain and squalls to many places in Guangdong, Guangxi and Hainan. More than 910 000 people were affected and the economic loss exceeded RMB 2.6 billion.

Doksuri (2305) formed as a tropical depression over the western North Pacific about 1 270 km east of Manila on the night of 20 July. It moved north-northwestwards and intensified gradually. Doksuri intensified into a typhoon on the night of 23 July and tracked northwestwards. It developed further into a super typhoon next night and attained its peak intensity with an estimated maximum sustained wind of 210 km/h near its centre on the morning of 25 July. Doksuri moved across Luzon Strait that night and the next morning, and turned to move north-northwestwards. During its passage across the northeastern part of the South China Sea, Doksuri once weakened into a severe typhoon on the night of 26 July but re-intensified into a super typhoon next night. Doksuri made landfall near Jinjiang of Fujian province on the morning on 28 July. It moved into inland and weakened further that day. It finally degenerated into an area of low pressure over Anhui the next morning.

According to press reports, Doksuri left at least 25 deaths and 52 injuries in the Philippines during its passage. Over 2.45 million people were affected, over 41 000 houses were damaged and economic loss exceeded PHP 5.4 billion. In Fujian, Zhejiang, Anhui, Jiangxi and Guangdong, around 2.95 million people were affected. More than 15 000 houses were damaged and economic loss exceeded RMB 14.7 billion. Besides, affected by the remnant of Doksuri, torrential rain wreaked havoc in many provinces and cities in East China, North China and Northeast China during 29 July – 1 August. In Beijing, some areas recorded maximum cumulative rainfall of more than 1 000 millimetres, causing 33 deaths, 18 missing and 1.29 million people affected.

Khanun (2306) formed as a tropical depression over the western North Pacific about 2 170 km southeast of Okinawa in the small hours on 27 July. It moved northwestwards or north-northwestwards towards the vicinity of the Ryukyu Islands and intensified gradually in the following four days. Khanun intensified into a super typhoon on the night of 31 July, and reached its peak intensity with an estimated sustained wind of 195 km/h near the centre the next morning. It then tracked west-northwestwards and weakened gradually. Khanun turned to move eastwards across the vicinity of the Ryukyu Islands from the afternoon of 3 August to 6 August. Khanun turned to move north-northwestwards again across the East China Sea in the following four days, and finally degenerated into an area of low pressure over the Korean Peninsula on the afternoon of 11 August.

According to press reports, Khanun brought very heavy rain and squalls to Japan. Parts of the southern Kyushu recorded cumulative rainfall of more than 1 000 millimetres, causing one death and 97 injuries. More than 210 houses were damaged. Water and electricity supply to more than 30 000 and 240 000 households were disrupted respectively. Economic loss exceeded 2 billion JPY. Khanun left two deaths in the Republic of Korea during its passage. There were also about 360 reports of damaged facilities. More than 15 000 people were evacuated. Economic loss exceeded 56 billion KRW.

Lan (2307) formed as a tropical depression over the western North Pacific about 790 km east of Iwo Jima in the small hours on 8 August. It then moved west-northwestwards and intensified gradually. Lan turned to move northwestwards or north-northwestwards towards Honshu, Japan on 10 August. Lan intensified into a severe typhoon the next day, and reached its peak intensity with an estimated sustained wind of 175 km/h near the centre in the morning. Lan weakened into a typhoon on the night of 12 August and continued to edge closer to Honshu, Japan in the following two days. Lan moved across Honshu, Japan on 15 August and finally evolved into an extratropical cyclone over the Sea of Japan on the afternoon of 17 August.

According to press reports, Lan left more than 60 injuries in Japan during its passage. 130 houses were damaged. Water and electricity supply to more than 7 000 and 100 000 households were disrupted respectively.

Originating from the eastern North Pacific, Dora (2308) moved across the International Date Line with severe typhoon intensity and entered the western North Pacific on the morning of 12 August. The maximum sustained wind near its centre was estimated to be 165 km/h at the time. It tracked northwestwards or west-northwestwards towards the vicinity of Wake Island. Dora weakened gradually in the following three days and finally degenerated into an area of low pressure over sea on the morning of 16 August.

Saola (2309) formed as a tropical depression over the western North Pacific about 670 km southeast of Gaoxiong on the night of 23 August and moved slowly at first. It then made an anti-clockwise loop over the seas east of Luzon and intensified rapidly in the following five days. Saola intensified into a super typhoon on the night of 26 August. Saola weakened from super typhoon into a severe typhoon twice in the following three days, but intensified into a super typhoon again on the evening of 29 August and tracked west-northwestwards across Luzon Strait. Saola attained its peak intensity with an estimated maximum sustained wind of 230 km/h near its centre in the small hours of 30 August. Saola maintained this intensity and entered the South China Sea later that day, making it the second strongest tropical cyclone in the South China Sea since the Observatory’s records began in 1950, just after Super Typhoon Rammasun in 2014. It edged closer to the coast of Guangdong gradually while maintaining super typhoon intensity on the next day. Saola turned to move westwards across the coastal waters of Guangdong on 1 September. It weakened rapidly on 2 September and made landfall near Yangjiang of Guangdong in the afternoon. Saola continued to move across the coast of western Guangdong afterwards and weakened into a tropical depression progressively. Saola entered Beibu Wan on the morning of 3 September and finally weakened into an area of low pressure that night.

According to press reports, Saola brought torrential rain and squalls to the northern part of the Philippines, causing 2 deaths, 3 injuries and 2 missing. More than 1.16 million people were affected, more than 7 800 houses were damaged and economic loss exceeded PHP 2.4 billion. Under the influence of the outer rainbands of Saola, there were 60 reports of flooding in Taiwan. Around 200 people were displaced and electricity supply to more than 10 000 households was disrupted; whereas in Fujian, about 450 000 people were affected, 170 000 people were displaced, more than 140 houses were damaged and economic loss exceeded RMB 870 million. There were over 16 000 reports of fallen trees in Zhuhai. About 70 vehicles were damaged and economic loss was around RMB 60 million. In Shenzhen, a large tree fell under strong winds and hit a passing vehicle, killing one person and injuring two people. Besides, six people were injured when Saola affected Macao. There were also 188 incident reports. 264 flights were cancelled at the Macau International Airport.

Damrey (2310) formed as a tropical depression over the western North Pacific about 1 260 km southeast of Iwo Jima on the night of 23 August and moved slowly at first. It started to pick up speed to track east-northeastwards and intensified gradually the next day. It turned to move northwestwards towards the seas east of Honshu of Japan in the following two days. Damrey intensified into a severe tropical storm on the afternoon of 26 August, and reached its peak intensity with an estimated sustained wind of 110 km/h near the centre the next night. Damrey then gradually turned to move northeastwards and finally evolved into an extratropical cyclone over the seas east of Japan on the morning of 29 August.

Haikui (2311) formed as a tropical depression over the western North Pacific about 760 km south-southeast of Iwo Jima on the night of 27 August. It moved westwards or west-northwestwards towards the southern part of Taiwan and intensified gradually in the following six days. Haikui intensified into a severe typhoon in the small hours on 3 September and attained its peak intensity over the seas east of Taiwan, with an estimated maximum sustained wind of 175 km/h near its centre before noon on that day. It then moved across the southern part of Taiwan and weakened gradually. Haikui weakened into a tropical storm when it moved across the Taiwan Strait on 4 September. Haikui made landfall near Dongshan in Fujian on the morning of 5 September. It then moved into inland eastern Guangdong and finally degenerated into an area of low pressure that night.

According to press reports, at least 143 people were injured when Haikui affected Taiwan. Water and electricity supply to more than 20 000 and 270 000 households were disrupted respectively. Around 8 000 people were displaced. Economic loss exceeded USD 43 million. In Fujian province, more than 1.59 million people were affected, more than 2 500 houses were damaged and economic loss exceeded RMB 5 billion. Besides, after Haikui has weakened into an area of low pressure over inland eastern Guangdong, its remnant continued to move westwards slowly and wreaked havoc in the coastal areas with torrential rain affecting many places in Guangdong and Guangxi provinces during 5 – 11 September. In Shenzhen, from the night of 7 September to the morning of 8 September, maximum 2-hour rainfall of 195.8 millimetres, 3-hour rainfall of 246.8 millimetres, 6-hour rainfall of 349.7 millimetres and 12-hour rainfall of 465.5 millimetres were recorded, all breaking their respective records since Shenzhen’s meteorological records began in 1952. Many metro stations were flooded and some of the lines were suspended in Shenzhen. Some flights at Shenzhen Airport were delayed. Water was discharged from Shenzhen Reservoir in the small hours on 8 September. In Fujian, Guangdong and Guangxi, Haikui left at least six deaths or missing. More than three million people were affected and economic loss exceeded RMB 15.8 billion.

Kirogi (2312) formed as a tropical depression over the western North Pacific about 1 110 km east of Guam in the small hours on 30 August. It moved northwards and intensified gradually. Kirogi turned to move north-northwestwards, intensified into a severe tropical storm and attained its peak intensity with an estimated maximum sustained wind of 90 km/h near its centre the next afternoon. It tracked northwestwards or west-northwestwards towards the seas south of Japan and weakened gradually in the following three days. Kirogi finally degenerated into an area of low pressure over the seas south of Japan on the afternoon of 4 September.

Yun-yeung (2313) formed as a tropical depression over the western North Pacific about 710 km south-southeast of Okinawa on the afternoon of 4 September. It moved northeastwards or north-northeastwards towards Honshu, Japan and intensified gradually. Yun-yeung intensified into a tropical storm the next night and attained its peak intensity with an estimated maximum sustained wind of 75 km/h near its centre on the morning of 6 September. It weakened gradually on 8 September and finally evolved into an extratropical cyclone in the vicinity of Honshu, Japan in the small hours of the next day.

According to press reports, Yun-yeung left 3 deaths and 21 injuries in Japan during its passage. More than 2 600 houses were damaged. Water and electricity supply to more than 170 and 20 000 households were disrupted respectively.

A tropical depression formed over the central part of the South China Sea about 320 km east-southeast of Da Nang in the small hours on 25 September, with an estimated maximum sustained wind of 45 km/h near its centre. It moved northwestwards or west-northwestwards that day and finally degenerated into an area of low pressure over the central part of Vietnam the next morning.

Koinu (2314) formed as a tropical depression over the western North Pacific about 1 920 km east of Manila on the night of 28 September. It then moved westwards and intensified gradually. It turned to move northwestwards across the seas east of the Philippines on the afternoon of 30 September and in the following three days. During this period, Koinu intensified into a severe typhoon on the afternoon of 2 October and attained its peak intensity with an estimated maximum sustained wind of 175 km/h near its centre that night. Koinu tracked westwards towards the vicinity of the southern part of Taiwan on 4 October. After moving across the southern part of Taiwan the next day, Koinu weakened into a typhoon and then moved west-southwestwards across the northern part of the South China Sea. Koinu intensified into a severe typhoon again on the night of 6 October and turned gradually to move west-northwestwards, edging slowly towards the coast of Guangdong. It further moved slowly towards the vicinity of the Pearl River Estuary with severe typhoon to typhoon intensity in the following two days. However, under the influence of the northeast monsoon, Koinu weakened rapidly and turned gradually to move southwestwards on 9 October. Finally, it degenerated progressively into an area of low pressure over the coastal waters of Yangjiang that night.

According to press reports, one person was killed and 399 people were injured when Koinu affected Taiwan. Water and electricity supply to more than 6 000 and 460 000 households were disrupted respectively. Around 3 000 people were displaced. Economic loss exceeded USD 18 million. In Macao, two people were injured during the passage of Koinu. There were also 19 incident reports, including one case of fallen tree and one case of landslide.

Bolaven (2315) formed as a tropical depression over the western North Pacific about 1 140 km east-southeast of Guam on the morning of 7 October. It moved slowly westwards at first. It tracked west-northwestwards or northwestwards towards the vicinity of Iwo Jima and intensified gradually in the following three days. Bolaven intensified into a super typhoon on the morning of 11 October and attained its peak intensity with an estimated maximum sustained wind of 250 km/h near its centre that night. Bolaven gradually turned to move northeastwards the next day and weakened in the following two days. Finally, it evolved into an extratropical cyclone over the western North Pacific on the night of 14 October.

Sanba (2316) formed as a tropical depression over the central part of the South China Sea about 220 km east of Da Nang on the afternoon of 17 October. It moved north-northwestwards towards the vicinity of Beibu Wan and intensified gradually. Sanba intensified into a tropical storm the next morning and attained its peak intensity with an estimated maximum sustained wind of 85 km/h near its centre on the night of 19 October. Sanba lingered over the vicinity of Beibu Wan and skirted past Leizhou Peninsula on 20 October. Finally, it degenerated into an area of low pressure over Beibu Wan that night.

According to press reports, under the influence of the torrential rain associated with Sanba and its remnant, there were severe flooding over many places in Guangdong, Guangxi and Hainan provinces during 17 – 21 October. Record-breaking rainfall was recorded at many meteorological stations. Among them, Beihai, Guangxi recorded a 24-hour rainfall of 780.3 millimetres, breaking respective record since meteorological records began in Guangxi. During the passage of Sanba in Guangdong, Guangxi and Hainan, four people were killed, more than 300 houses collapsed and more than 2.13 million people were affected. The economic loss exceeded RMB 5.8 billion.

NOVEMBER

No tropical cyclone formed over the western North Pacific and the South China Sea in November 2023.

DECEMBER

Jelawat (2317) formed as a tropical depression over the western North Pacific about 1 400 km southeast of Manila in the small hours on 17 December and moved westwards towards the southern part of the Philippines. Jelawat attained its peak intensity with an estimated maximum sustained wind of 55 km/h near its centre that morning. Jelawat moved into Mindanao of the Philippines the next day. Finally, it degenerated into an area of low pressure over the region in the small hours on 19 December.

According to press reports, at least one person was found missing in the Philippines during the passage of Jelawat. Several houses were damaged and electricity supply was disrupted in many towns. More than 11 000 people needed to be evacuated.