As of October 16, a tropical depression has formed off the eastern coast of the Philippines. It is expected to strengthen into a storm within the next one or two days, with a 70–80% probability. The system is forecast to move toward the northeastern area of the northern East Sea around October 19–20.

Due to the impact of this tropical depression, which may intensify into a storm, wind speeds across the northern and central East Sea (including the Hoang Sa Islands) are expected to increase starting from the afternoon of October 18, accompanied by rough seas.

However, Mr. Hien noted that cold air from the north is expected to surge southward just as the storm moves into the East Sea. This interaction may cause the storm to weaken before reaching land.

Over the same period, there is little to no likelihood of significant rainfall or flooding in the northern region or the Red River system.

Cold air arrival and storms in the north

From the night of October 18, northern Vietnam will begin to experience the effects of a cold air mass, which will be further reinforced between October 20 and 25. This will bring cooler nighttime and early morning temperatures, with mountainous areas potentially experiencing cold spells.

In the Gulf of Tonkin, from October 20, northeast winds may strengthen to levels 6–7, with gusts exceeding level 8. Wave heights may reach 2–4 meters, resulting in rough seas.

Heavy rainfall forecast for central Vietnam: Focus from Ha Tinh to Quang Ngai

From October 16 to 18, the region stretching from Quang Tri to Quang Ngai will experience moderate to heavy rain and thunderstorms, with accumulated rainfall ranging from 70–150mm. In some locations, rainfall could exceed 350mm, and in parts of Hue, over 500mm.

After October 19, scattered moderate to heavy rain is expected to continue. Critically, from October 23 to 26, the central provinces will be impacted by a combination of cold air and upper-level easterly disturbances.

“This is a classic weather pattern in Vietnam. Combined with the country’s topography, it has the potential to generate heavy rain and severe flooding across river basins from Ha Tinh to Quang Ngai,” Mr. Hien emphasized.

Details on rainfall and flood warnings will be provided in subsequent short-term forecasts as required.

Severe cold spells may begin in late December

Looking further ahead, Mr. Hien noted that the probability of La Nina conditions continuing over the next three months is estimated at 60–75%.

In addition, up to three more tropical storms or depressions are expected to form over the East Sea, with one or two potentially affecting Vietnam’s mainland.

He also forecast that cold spells in northern Vietnam could begin in the latter half of December 2025.

Rainfall is expected in the central region, especially from Ha Tinh to Da Nang, as well as in Khanh Hoa and the eastern parts of Quang Ngai and Dak Lak.

Meanwhile, large-scale flooding in northern rivers is unlikely. However, flood peaks in central rivers may reach alarm levels 2–3, and in some areas, exceed level 3. These may coincide with reservoir water accumulation periods, increasing the risk of late-season floods.

In the Mekong Delta, water levels at Tan Chau and Chau Doc stations are receding and expected to remain low through the end of December. During the 2025–2026 dry season, salinity intrusion is forecast to be milder than in recent years and lower than levels recorded in 2024–2025.

Mr. Hien stressed that the Meteorological and Hydrological Administration issued these early forecasts to help ministries, sectors, and localities proactively monitor developments and implement timely and effective disaster response measures to protect lives and property.

Bao Anh