Forecasts for the last three months of the year indicate that the South China Sea will experience more storms and tropical depressions than the long-term average, with 2-3 of these potentially affecting the mainland.
The Institute of Meteorology, Hydrology and Climate Change reported that the El Niño-Southern Oscillation (ENSO) is currently in a neutral state, with sea surface temperatures in the equatorial and central Pacific ranging from -0.5 to 0.5 degrees Celsius from mid-August to early September.
This agency predicts a transition to a La Niña state during the months of October to December, with a probability of approximately 50-70%. The forecast for tropical cyclones in the South China Sea affecting Vietnam is around 4-5 storms in the South China Sea, with 2-3 impacting the mainland.
Ha Long (Quang Ninh) devastated after Typhoon Yagi. (Photo: Giang Huy).
The National Center for Meteorological Forecasting has stated that the La Niña phenomenon will continue through the last three months of 2024, leading to a more complex development of storms and tropical depressions in the South China Sea, with a likelihood of being 1.9 storms higher than the long-term average, primarily affecting the Central region and southern provinces. “Precautions are necessary as storms and tropical depressions may form directly over the South China Sea,” the center noted.
Increased Rainfall
According to forecasts, in October and November, the total rainfall in the Northern region is expected to exceed the long-term average by 10-20%, with lower mountainous areas seeing an increase of 5-10%. In December, rainfall is expected to be between 20-40 mm, which is lower than the long-term average by 5-10 mm.
The Central region will be the focus of rainfall over the next two months. Forecasts indicate that rainfall in October and November will exceed the long-term average by 10-30%. In December, Quang Binh and Quang Tri provinces are expected to receive 100-200 mm of rain, which is higher than the average by 10-15 mm; Thua Thien Hue and Quang Binh provinces will see rainfall totals of 250-500 mm, exceeding the average by 30-60 mm. Ninh Thuan and Binh Thuan provinces will receive 30-80 mm of rain, which is higher than the average by 15-30 mm.
The Central Highlands and Southern region will also experience rainfall higher than the long-term average by 5-20% during the same period. In December, the Central Highlands is expected to receive 30-50 mm of rainfall, while some areas in the southern Central Highlands and the Southern region may see totals of 50-80 mm, exceeding the average by 10-30 cm.
Flooding in Thai Nguyen after Typhoon Yagi. (Photo: Nguyen Dong).
Increased Flooding
Due to rainfall exceeding average levels, flooding across the country is expected to be complex. In the coming three months, water flow on rivers in the Northern region is expected to be 10-20% higher than the long-term average, particularly in Tuyen Quang and Thac Ba reservoirs on the Gam and Chay rivers, which may exceed normal levels by 30-70%.
North Central region until November may see 1-2 flood events on rivers in Thanh Hoa, and 3-4 flood events in Nghe An and Ha Tinh. The peak flood levels on the downstream Ma River may reach alert level one, while the Ca and La rivers may exceed alert level two. By December, river levels are expected to gradually decrease.
Central region is expected to experience 3-5 major flood events from October to December, primarily in October and November. Flood levels could reach alert level three on some rivers, with the 2024 peak flood levels projected to be at or above average.
South Central region could see 2-4 flood events from October to December, with flood peaks on rivers in Binh Dinh and Khanh Hoa reaching alert level two, and some areas exceeding alert level three. Rivers in Phu Yen, Ninh Thuan, and Binh Thuan may reach alert level two. Flow rates on the upper rivers are expected to be 20-50% above average.
Floodwaters reaching the rooftops of homes in Tan Hoa tourist village on September 21. (Photo: Vo Thanh).
From late September to December, the total flow of the Mekong River into the Mekong Delta is expected to change slowly with a rising trend, with the total flow to the Mekong Delta in September 2024 being 5-10% lower than the long-term average. From October to December 2024, the total flow to this region is expected to be at average levels.
Strong Northeast Monsoon at the End of the Season
The Institute of Meteorology, Hydrology and Climate Change forecasts that this winter’s northeast monsoon will show changes in intensity. In the early months of the season (November-December 2024), the northeast monsoon will be weaker than or similar to the long-term average. However, from January to March 2025, the northeast monsoon may strengthen and exceed average levels. Intense cold spells are expected to occur during the main winter months starting from late December.
The average temperature in October across the country is expected to be about 0.5-1 degrees Celsius higher than the long-term average. In November and December, temperatures are likely to decrease toward the long-term average. Specifically, in the Northern and North Central regions, temperatures in the last two months of the year may be about 0.5 degrees Celsius lower than average.
Since the beginning of 2024, there have been four storms in the South China Sea, including Typhoon Yagi, which significantly impacted the entire Northern region, causing severe human loss with 299 deaths, 34 missing persons, and over 70,000 homes inundated. Economic losses exceed 60 trillion VND, making it the most devastating storm to date.
