Why storms are hitting the East Sea so often this year

Since June, the region has seen storm after storm sweep in. September alone recorded four typhoons: Tapah Mitag, Ragasa, and the soon-to-arrive Bualoi, plus a tropical depression. That is two more than the average for this month, according to the National Center for Hydro-Meteorological Forecasting. In the past five years, September has rarely seen more than six storms total, making 2025 an outlier.

Mai Van Khiem, director of Vietnam’s National Center for Hydro-Meteorological Forecasting, said the direct trigger is the unusually active intertropical convergence zone: a band of low pressure circling the equator. This belt creates small atmospheric disturbances that can rapidly grow into tropical depressions and then full typhoons.

Storms need two key ingredients: heat and atmospheric dynamics. Just 26–27 degrees Celsius sea surface temperature is enough to spark development, but current waters east of the Philippines and across the northwest Pacific are hovering around 28–29 degrees. That extra warmth provides powerful fuel for cyclones to intensify quickly.

At the same time, seasonal winds are amplifying the effect. September marks the transition from summer to autumn, when the southwest monsoon collides with easterly winds from the subtropical high. This interaction spins up medium-scale vortices that help smaller disturbances mature into storms at an unusually rapid pace.

ENSO (El Nino–Southern Oscillation) is currently in a neutral phase, with a possible La Nina developing later this year. That pattern alone suggests storm activity will remain at or above normal, with 12–13 systems in total and up to seven hitting Vietnam directly.

But climate change adds a more worrying dimension. Warming seas and higher atmospheric moisture are providing more energy for cyclones, said Truong Ba Kien, deputy director of the Center for Meteorology and Climate Research. Recent studies confirm that strong and even "super typhoons" have become more common over the past few decades, and that trend is expected to accelerate with global warming.

Central Vietnam, often in the direct path of Pacific storms, is now entering its most dangerous months. Historically, the peak runs from September to November, sometimes extending into December. With abnormally high sea temperatures, the chances of powerful storms striking in October and November are "very real," Khiem said, recalling that many of the strongest typhoons in Vietnam's history formed east of the Philippines before slamming into the central coast.

The biggest threats for the coming months include torrential rain, flash floods and landslides in the central provinces and Central Highlands; storm surge, high waves and tidal flooding along the coast; and cumulative flooding when storms arrive in quick succession. These hazards also endanger reservoirs, embankments and dikes.

Both Khiem and Kien urged local authorities and communities to stay on high alert. Forecasts are updated every 6–12 hours, and people are advised to secure homes, reinforce boats, trim trees, check reservoirs and stock up on essential supplies. Provinces are being told to prepare evacuation plans, food, clean water and backup power in case of prolonged disruptions.

Sectors from transport to agriculture and power are also drawing up emergency plans: harvesting crops and aquaculture early in high-risk zones, lowering water levels in reservoirs, and readying crews to handle infrastructure damage.