Vietnam is a southeast Asian country, and is the easternmost country of mainland Southeast Asia. Because it is located in the easternmost part and borders the South China Sea, it is often affected by tropical cyclones. Tropical cyclones in this area are considered to be part of the Northwest Pacific basin. There are about 11 to 13 tropical cyclones entering the South China Sea during the period from June to November every year. [1]
Every year, there are about 4 to 6 tropical cyclones that make landfall or directly affect the mainland. According to the climate law, the tropical cyclones season in Vietnam gradually slows down from North to South, with the highest storm frequency in the coastal provinces from Quảng Ninh to Thanh Hoá and the lowest in the area from Lâm Đồng to Cà Mau and An Giang. Tropical cyclone have a strong impact and cause damage to both the economy and life of this country.
Any tropical cyclone entering the South China Sea west of 120°E and north of 5°N are monitored and reported by the National Center for Hydro-Meteorological Forecasting (NCHMF) [2] together with the Japan Meteorological Agency (JMA) and the Joint Typhoon Warning Center (JTWC). NCHMF also regularly issues weather bulletins and advisories to the public, especially during storms. The Vietnamese government also pays attention to storm and tropical depression prevention and control, and natural disasters in general. The country has established the National Civil Defense Steering Committee (formerly the National Steering Committee for Natural Disaster Prevention and Control; National Committee for Incident, Disaster Response and Search and Rescue) to develop and implement plans to respond to storms, tropical depressions and other types of natural disasters. A five-level disaster risk warning scale, issued under Decision No. 18/QD-TTg in 2021 of the Prime Minister of Vietnam, will apply to all or part of the provinces and localities affected by tropical cyclones when they are forecast to have the potential to affect mainland Vietnam.
Bão comes from the word "暴". (Hán-Việt: bạo). According to Hoang Phê (2003), "Bão" means "a large-scale whirlwind in an area with very low air pressure, often originating from the open sea, with violent destruction due to strong winds and heavy rain"
Nguyễn Đức Ngữ (1998) defines cyclones as atmospheric disturbances with pressure decreasing from the edges to the center, and in the Northern Hemisphere the wind blows counterclockwise. [3]
The National Center for Hydro-Meteorological Forecasting (NCHMF) defines storms and tropical depressions, collectively known as tropical cyclones, as "a whirlwind, up to hundreds of kilometers in diameter, forming over tropical seas; in the Northern Hemisphere, winds blow into the center in a counterclockwise direction; the atmospheric pressure in the storm is much lower than the surrounding area and is usually lower than 1000mbar". [4] Depending on location and intensity, tropical cyclones are known by different names. [5] In the Northwest Pacific basin, including Vietnam, meteorologists use the term typhoon (in English) to refer to tropical storms with minimum wind speeds of 118 km/h (73 mph), [6] [7] according to the regulations of the Japan Meteorological Agency (JMA), the unit established the Regional Specialized Meteorological Center (RSMC Tokyo) of the Northwest Pacific as assigned by the World Meteorological Organization (WMO).
Category | Sustained winds | Beaufort number |
---|---|---|
Tropical Depression | ≤33 knots ≤61 km/h | 6-7 |
Tropical Storm | 34–47 knots 62–88 km/h | 8-9 |
Severe Tropical Storm | 48–63 knots 89–117 km/h | 10-11 |
Typhoon | 64–99 knots 118–183 km/h | 12-15 |
Super Typhoon | ≥100 knots ≥184 km/h | ≥16 |
In Vietnam, as in the Northwest Pacific basin, tropical cyclone are generally active year-round from January to December. [8] However, the tropical cyclone season in Vietnam is usually considered to be from June to November. [9] On average, the South China Sea records 11 to 13 tropical cyclone in many years [10] and the tropical cyclone season in the South China Sea is assessed to slow down from North to South. [11] The strongest activity is in July, August, September, and October with an average of about 2 tropical cyclones per month. [12] However, there are some years when the South China Sea has many storms. In 2017, a record 20 tropical cyclones (including 16 typhoons/storms and 4 tropical depressions) were recorded. [13] [14] [15] Conversely, there are also years with few storms, in which the year with the fewest storms in the South China Sea was 1969 with a total of 5 tropical cyclones. [16] A study was investigated in the correlation of rainfall and tropical cyclones during El Niño and La Niña seasons, and showed that there is an increase of rainfall and tropical cyclones during La Niña seasons. [17]
Vietnam currently uses the Beaufort wind scale to measure storm intensity. Before 2006, the wind scale in Vietnam only used up to level 12 and above. After typhoon Chanchu and Xangsane in 2006, the Vietnamese Government issued Decision 245/2006/QD-TTg, stipulating the expansion of the wind scale in Vietnam to level 17 (maximum 220 km/h). [18] Currently in Vietnam, according to Decision 18/2021/QD-TTg on forecasting, warning, transmitting information on natural disasters and disaster risk levels issued by the Prime Minister, the tropical cyclone scale in Vietnam includes 5 types: tropical depression, tropical storm, servere tropical storm, typhoon and super typhoon. The wind scale in Vietnam according to this regulation also stops at level 17.. [19]
Region | Area |
---|---|
I | Northeast (5 provinces) |
II | Northwest (3 provinces) |
III | Northern Delta, Midlands and Thanh Hoá (8 provinces) |
IV | Nghệ An to Huế (4 provinces) |
V | Đà Nẵng to Gia Lai (3 provinces) |
VI | Đắk Lắk to Khánh Hoà (2 provinces) |
VII | West of Quang Ngai, Gia Lai, Dak Lak and Lam Dong provinces |
VIII | Lâm Đồng to Cà Mau—An Giang and Southern (9 provinces) |
After Super Typhoon Haiyan in 2013, the Vietnamese Government began developing scenarios to respond to typhoons and super typhoons. Decision No. 1857/QD-BTNMT dated August 29, 2014 of the Ministry of Natural Resources and Environment divided the storm zone in Vietnam into 5 regions: from Quảng Ninh to Thanh Hoá, Nghệ An to Thừa Thiên-Huế, Đà Nẵng to Bình Định, Phú Yên to Khánh Hoà and Ninh Thuận to Cà Mau. [20] By 2016, the Ministry of Natural Resources and Environment continued to divide Vietnam into 8 regions. [21] [22] These 8 regions include: the Northeast region; the Northwest region; the Northern plains, midlands and coastal areas from Quang Ninh to Thanh Hoa; from Nghệ An to Huế; from Đà Nẵng to Bình Định (from July 1, 2025, Gia Lai province); from Phú Yên to Ninh Thuận (from July 1, 2025, Dak Lak province and Khánh Hoà province); the Central Highlands and the South (including Bình Thuận province, from July 1, 2025, Lâm Đồng province) [23]
However, according to the decentralization of hydrometeorological management in Vietnam from 2025, 3 hydrometeorological stations are arranged in 3 regions: Northern Hydrometeorological Station; Central Hydrometeorological Station; Southern Hydrometeorological Station. [24] Previously, according to Decision 03/2018/QD-TTg, the Northern region of Vietnam was divided into 4 hydrometeorological stations including Northwest, Northeast, Viet Bac and Northern Delta. [25] By 2023, Vietnam will have 7 meteorological stations including the Northern Mountains, Northern Midlands and Delta, North Central, Central Central, South Central, Central Highlands and South. [26] In weather forecasting and warning, Vietnam is divided into 6 regions including Northwest, Northeast, Thanh Hoa to Hue, Da Nang to Lam Dong, Central Highlands and South. [27] In addition, there are many different studies for different ways of distributing storm landing zones in Vietnam. [28] [29]
Rank | Name | Year | Pressure | Source | |
---|---|---|---|---|---|
Value | In | ||||
1 | Yagi (Super Typhoon No.3) | 2024 | 955,2 hPa | Bãi Cháy (Quảng Ninh) | |
2 | Cecil (Typhoon No.8) | 1985 | 959,9 hPa | Đông Hà (Quảng Trị) | [30] [31] |
3 | Xangsane (Typhoon No.6) | 2006 | 963,3 hPa | Đà Nẵng | [32] |
4 | Sarah (Typhoon No.2) | 1977 | 963,4 hPa | Phù Liễn (Hải Phòng) | [33] |
5 | Doksuri (Typhoon No.10) | 2017 | 966,6 hPa | Ba Đồn (Quảng Bình old) | [34] |
6 | Wayne (Typhoon No.5) | 1986 | 967,4 hPa | Nam Định (old) | [35] |
7 | Vera (Typhoon No.3) | 1983 | 968,3 hPa | Cửa Ông (Quảng Ninh) | [36] |
8 | Frankie (Typhoon No.2) | 1996 | 969 hPa | Văn Lý (Nam Định old) | [37] |
9 | Wutip (Typhoon No.10) | 2013 | 969,2 hPa | Đồng Hới (Quảng Bình old) | [38] |
10 | Molave (Typhoon No.9) | 2020 | 971,9 hPa | Quảng Ngãi | [39] |
On average, Vietnam is affected by 6–8 tropical cyclones every year.
Month | Number of Storms |
---|---|
January | |
February | |
March | |
April | |
May | |
June | |
July | |
August | |
September | |
October | |
November | |
December |
The following list are the ten deadliest storms that impacted Vietnam. Total number of deaths recorded are only from the country itself.
Rank | Name | Year | Number of Deaths |
---|---|---|---|
1 | Joan | 1964 | 7,000 |
2 | Linda | 1997 | 3,111 |
3 | "Haiphong" | 1881 | 3,000 |
4 | Cecil | 1985 | 769 |
5 | Cecil | 1989 | 751 |
6 | Wayne | 1986 | 401 |
7 | Yagi | 2024 | 322 |
8 | Lex | 1983 | 252 |
9 | Chanchu | 2006 | 241 |
10 | Ketsana | 2009 | 179 |
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