In the second half of September, the East Sea has experienced a surge in storm activity, with several storms directly affecting Vietnam’s mainland. Meteorological experts have analyzed the causes and offered forecasts for the rest of the year.

Typhoon Bualoi is expected to enter the East Sea on the night of September 26, becoming the 10th named storm of 2025. Forecasts indicate the storm could intensify to category 12-13, with gusts reaching category 16. In the most extreme scenario, experts warn that Bualoi could head toward Central Vietnam. However, the storm’s path remains unpredictable and will be continuously updated by the National Center for Hydro-Meteorological Forecasting.

In September 2025 alone, the East Sea has recorded four typhoons - Tapah, Mitag, Ragasa, and the incoming Bualoi - along with one tropical depression. This total is two more than the multi-year average for the month. Notably, three of these storms have formed within just the past week.

According to the National Center for Hydro-Meteorological Forecasting, in recent years the East Sea has typically seen between 4 to 6 storms by the end of September, with a historical maximum of 6. However, in 2025, the number of storms and tropical depressions has already reached 10 (including the projected Bualoi storm), exceeding the long-term average by 4 to 5.

Meteorologists attribute the unusually high number of storms in September to the intense and stable activity of the Intertropical Convergence Zone (ITCZ) near the equator. This zone is highly conducive to the formation of atmospheric disturbances and small cyclonic systems - key precursors to tropical depressions and storms.

Many recent storms, including Ragasa and the soon-to-arrive Bualoi, originated from this mechanism.

Mai Van Khiem, Director of the National Center for Hydro-Meteorological Forecasting, explained that two essential conditions for storm formation are thermal energy and atmospheric dynamics. Sea surface temperatures only need to reach 26–27°C to trigger storm development. Currently, sea temperatures in the northwestern Pacific and east of the Philippines range from 29–30°C - ideal for storm formation and intensification in the East Sea.

In terms of atmospheric dynamics, September marks the seasonal transition from summer to autumn. During this time, the southwest monsoon is strong and interacts with easterly winds from the subtropical high-pressure system. These interactions generate medium-scale cyclonic systems, which can allow small sea disturbances to quickly evolve into tropical depressions and storms.

Experts predict that the number of storms or tropical depressions forming in the East Sea and potentially affecting Vietnam will remain higher than average through the end of the year. Historically, the East Sea sees an average of 4.5 storms per year, with about 1.9 making landfall in Vietnam.

Climatologically, storms that form late in the year tend to impact areas from Central Vietnam southward. September typically marks the beginning of the storm and flood season for Central Vietnam, with the peak stretching from September to November - and potentially lasting into early December.

Given current high sea surface temperatures, experts warn that powerful storms in October and November are entirely possible.

Additionally, this year’s cold air is forecast to arrive earlier than usual. When storms interact with incoming cold fronts and the mountainous terrain of the Truong Son range, they can trigger dangerous weather patterns - particularly complex and widespread flooding in Central Vietnam.

In light of the growing risks posed by climate change, the National Center for Hydro-Meteorological Forecasting has urged residents and local authorities in Central Vietnam to closely monitor official forecasts and proactively prepare disaster response plans to minimize loss of life and property.

Bao Anh