Why are more typhoons heading north in Vietnam this year ?

Six out of the ten storms that have hit Vietnam this year, including the most recent, Typhoon Matmo, have moved northward, primarily due to the influence of the subtropical high-pressure system and cold air.

October is typically the peak month for storms making landfall in Vietnam.

Storms usually form east of the Philippines, travel west-northwest, cross Luzon Island, enter the South China Sea, which Vietnam calls the East Sea, and then head toward Vietnam’s central coast. This pattern is driven by the subtropical high-pressure system (a high-pressure area around latitudes 25–35), which blocks storms from the east, and cold air from the north, creating a west-northwest steering flow.

However, Typhoon Matmo, which weakened into a tropical depression on Monday morning, defied this usual path and moved north toward the Vietnam-China border. So far this year, six out of the ten storms impacting Vietnam have followed this northern course: Wutip, Wipha, Kajiki, Tapah, Ragasa, and Matmo.

Nguyen Van Huong, Head of the Weather Forecasting Department at the National Center for Hydro-Meteorological Forecasting, explained that the increased frequency of storms moving northward this year is due to the influence of the subtropical high-pressure system and cold air.

While storms in October generally follow a west-northwest path, driven by the subtropical high-pressure system and cold air from the north, Typhoon Matmo veered off this route and headed toward the Vietnam-China border.

This deviation is attributed to the subtropical high-pressure system moving southwest and cold air from the north being too weak to push the storm southward.

Truong Ba Kien, Deputy Director of the Center for Meteorology and Climate Research at the Institute of Meteorology, Hydrology, and Climate Change, cited two primary reasons for Matmo’s northern movement.

First, synoptic charts (hourly composite weather maps) show that the subtropical high is pushing northwestward and is forecast to retract eastward and shift south, which allowed Matmo to turn north.

Second, the cold air in the north remains weak, preventing the storm from being steered southward toward central Vietnam, he said, sharing the view of Huong.

« This combination of factors caused Matmo to avoid making landfall in central Vietnam as usual and instead move north, affecting the Gulf of Tonkin and northern regions, » said Kien.

Historically, October storms tend to follow a west-northwest path toward central Vietnam. However, long-term storm tracks and average path maps over the past 40 years show a distinct branch that turns northward through Luzon into the South China Sea, reaching Hainan Island or the Leizhou Peninsula, and then the Gulf of Tonkin. While this northern branch occurs less frequently than the central Vietnam path, it is not rare and recurs each storm season.

Kien pointed to past examples of storms taking the northern path, such as Typhoon Sarika in October 2016, which formed east of the Philippines, crossed Luzon, made landfall in Hainan, and then impacted northern and north-central Vietnam, bringing heavy rainfall due to interaction with cold air.

Similarly, Typhoon Khanun in October 2017 intensified in the northern South China Sea, moving toward Hainan-Guangdong, causing strong winds and high waves in the Gulf of Tonkin and rainfall in Vietnam’s north.

Typhoon Nesat, which occurred in late September and early October 2011, followed a similar pattern, affecting Luzon before moving toward Hainan-Guangdong and bringing strong monsoon winds and heavy rain to northern Vietnam.

By Gia Chinh – VnExpress.net – October 7, 2025