Climate of Vietnam
[7] From 1960 to 2011, high increases of 0.24 °C and 0.28 °C per decade are found at Vung Tau and Ca Mau stations, respectively, located in the South Coast.
[8] From 2007 to 2008, the flooding in the central provinces exceeded that of past 48 years; the northern part of Vietnam encountered an unprecedented cold wave, lasting for 38 days, resulting in 30 million US dollars Crop and livestock losses.
[1]: 27 This leads to four distinct seasons of which Winter (November–March) and Summer (May–September) are the major ones while Spring (April) and Fall (October) are transitional ones.
[1]: 28 In addition, during summer, Vietnam is influenced by tropical air from the Bay of Bengal which occurs when a continental low pressure originating from South Asia (South Asian continental low) moves eastwards towards Vietnam, covering almost all of Vietnam and southern China; this causes hot, dry weather in the North Central Coast as westerly winds descend and warm adiabatically on the eastern slopes of the Annamite Range (Truong Son range).
[1]: 28 In general, the northern parts of the country have four seasons: winter, spring, summer, and fall (autumn).
[11] Mean annual temperatures in the country, based on meteorological data from weather stations range from 12.8 to 27.7 °C (55 to 82 °F) in Hoàng Liên Sơn.
[4][6] In winter, mean temperatures range from 1 to 28 °C (34 to 82 °F), which decreases from south to north, and/or as one climbs up its mountains, and vice versa.
[1]: 31 Consequentially, the south reaches their highest temperatures in late winter while in the north, they occur in July and August due to this.
[1]: 37 In the highest peaks in the north in Sa Pa, Tam Dao, and Hoang Lien Son, snowfall can occur.
[1]: 35 For the South Central Coast, the rainy season begins in August and September, reaching a peak in October and November before ending in December.
[1]: 35 In the Central Highlands, the rainy season begins in April and May that peaks in August before ending in October and November.
[2]: 24 The Northwest region includes the provinces of Lai Châu, Sơn La, and Điện Biên.
[1]: 39 The climate is characterized by cold, dry (little drizzly rain), sunny winters in which hoarfrost is common in many years.
[1]: 41 Owing to diverse terrain and climate in this region, this leads to different types of forests being present.
[15]: 10 The Northeast region includes the northern and northeastern provinces: Lào Cai, Yên Bái, Hòa Bình, Hà Giang, Tuyên Quang, Phú Thọ, Cao Bằng, Lạng Sơn, Bắc Kạn, Thái Nguyên, and Quảng Ninh.
However, unlike the northwest, dry conditions are rare due to a low frequency of westerly winds.
[15]: 9 In the Hoang Lien Son mountains, winters are cold where snowfall and hoarfrost can occasionally occur.
[19] The North Delta includes the provinces of Phú Thọ, Vĩnh Phúc, Bắc Giang, Bắc Ninh, Hanoi, Hai Phong, Hải Dương, Hưng Yên, Hà Nam, Nam Định, Thái Bình, and Ninh Bình.
[1]: 40 Winters are characterized as being cold with large amounts of drizzle and little sunshine while summers are hot, rainy with few dry days.
[1]: 40 Winters are characterized by cold, cloudy weather with frequent drizzle, being under the influence of the northeast monsoon.
[1]: 40 [15]: 10 Compared to other regions in Northern Vietnam, winters are warmer and wetter due to the influence of the Truong Son Mountains that block the northeast monsoon coming from the Gulf of Tonkin.
[1]: 40 Winters are warm and sunny while summers are hot and dry owing to a high frequency of the westerly winds.
[22] In contrast to the North Central Coast, the temperature difference between the coldest and hottest months is much smaller.
[22] As one progresses southward, the rainy season shifts away from the end of year (occurs more earlier) and vice versa.
[1]: 29 The lowest air pressure ever recorded was at Sa Pa on 24 July 1971 with a reading of 827.0 hPa (24.42 inHg).
[1]: 29 The highest wind recorded in Vietnam was 59 m/s (190 ft/s) in Quy Nhon in September 1972 although wind velocities over 40 m/s (130 ft/s) have been recorded in the North Delta (Red River Delta), and coastal areas of Quảng Ninh Province[1]: 29 Vietnam is among the most affected countries by global climate change.
[26] A large number of studies show that Vietnam is experiencing climate change and will be severely negatively affected in coming decades.
These negative effects include sea level rise, salinity intrusion and other hydrological problems like floods, river mouth evolution and sedimentation.
Natural hazards such as cold waves, storm surges will increase in frequency, with negative effects on the country's development, infrastructure and economy.
Climate extremes include heat waves, cold surges and frosts, floods, droughts, and severe storms.
