Tracking Typhoon Koto: The Harp's Fury Across the South China Sea
In the waning days of November 2025, as the Pacific typhoon season stretched beyond its typical peak, a new system took shape east of the Philippines. This storm, christened Koto—a name meaning "harp," plucked from the constellation Lyra—would weave a complex and damaging path through island communities and across the open sea. While never among the season's most powerful cyclones, the story of Typhoon Koto is one defined by relentless rainfall, a staggering series of landfalls, and the compounding vulnerabilities of regions already reeling from a relentless year of weather disasters. This is the meteorological and human tale of a storm that underscored how hydrological hazards, not just wind, dictate true impact.
The Genesis and Erratic Path of a Late-Season Storm
Typhoon Koto's origins can be traced to a modest area of low pressure near Palau, designated Invest 92W by forecasters on November 22. Under marginally favorable conditions of warm seas and low wind shear, it steadily organized. By the evening of November 23 (UTC), it had developed into a tropical depression, promptly named Verbena by the Philippine Atmospheric, Geophysical and Astronomical Services Administration (PAGASA) as it headed toward the archipelago.
What followed was a marathon of land interaction. In a 24-hour period between November 24 and 25, the then-Tropical Storm Koto made an astonishing seven recorded landfalls across the central Philippines: from Surigao del Sur through Bohol, Cebu, Negros Oriental, Guimaras, Iloilo, and finally Palawan. Each transit over land sapped its strength but also wringed out torrential moisture, setting the stage for its primary destructive mode: floods. Emerging into the South China Sea on November 26, Koto found a brief window to intensify, reaching its peak as a Category 1-equivalent typhoon on November 27, with sustained winds estimated at 150 km/h (90 mph).
However, Koto's journey was far from over. Its steering currents collapsed, causing the storm to stall and meander erratically west of the Philippines. This stalling, a phenomenon scientists are increasingly studying in a warming climate, allowed Koto to churn over the same ocean areas, upwelling cooler water that ultimately sapped its power. Coupled with intrusions of dry air and increasing wind shear, Typhoon Koto began a gradual weakening trend, downgrading to a tropical storm and then a depression as it finally drifted towards Vietnam in early December.
A Deluge of Consequences: Regional Impacts Unpacked
The legacy of Typhoon Koto was written in water, not wind. Its slow movement and prolonged interaction with the Philippine landmass unleashed catastrophic rainfall. The numbers tell a stark story: over 275,000 people were affected across the Visayas and Mindanao, with nearly 83,000 forced to evacuate. While only a handful of homes were destroyed by winds, the hydrological impact was severe. Waist-deep floods inundated Bohol, and landslides triggered by sodden mountainsides blocked 37 roads and 5 crucial bridges. Maritime travel ground to a halt with 79 ports closed, stranding thousands. Tragically, two individuals were reported missing in the Negros Island Region, swept away by flash floods.
For Vietnam, Typhoon Koto (known locally as Storm No. 15) arrived as a dangerous, rain-laden remnant. It compounded recovery efforts from earlier floods that had already claimed nearly 100 lives in the country that year. Although Koto had weakened significantly before approaching the coast, its broad circulation and abundant moisture fueled intense rainfall in the south-central provinces. This led to further disasters on the water, with sinking boats claiming three to four lives. The storm's contribution pushed Vietnam's annual toll from storms and floods in 2025 past a staggering US$3.2 billion in economic losses. Koto was a poignant reminder that even a dissipating system can be deadly.
Forecasting, Preparedness, and the Climate Context
The forecasting of Typhoon Koto presented challenges, particularly predicting its stalling phase over the South China Sea. Agencies like the Japan Meteorological Agency (JMA), the Joint Typhoon Warning Center (JTWC), and PAGASA provided consistent tracking, but the storm's unpredictable slowdown tested models. In response, Philippine authorities acted decisively, raising Tropical Cyclone Wind Signals across more than 20 provinces and executing pre-emptive evacuations that undoubtedly saved lives. Vietnam's National Civil Defense Steering Committee similarly activated response plans days in advance, focusing on moving vessels to safety and preparing coastal communities for heavy rain.
Meteorologically, Typhoon Koto was an intriguing anomaly. The 2025 season was characterized by a neutral El Niño-Southern Oscillation (ENSO) phase and a negative Pacific Decadal Oscillation (PDO), conditions that typically suppress overall activity. Yet, Koto became the season's 27th named storm and 14th typhoon, contributing to a total that far exceeded averages. Its late-November formation and intensification defied seasonal expectations, fueling discussions among scientists about shifting patterns and the increasing role of high ocean heat content—a signature of anthropogenic climate change—in fueling storms outside traditional windows.
The Lingering Echo of the Storm
As the clouds dispersed and floodwaters receded in early December, the work of recovery began. Communities in the Philippines cleared debris and restored links, while in Vietnam, the focus remained on search and rescue operations and mitigating the next flood pulse. Typhoon Koto may not have been the strongest storm of 2025, but its impacts were deeply felt. It exemplified the "rainmaker" typhoon, a type of event that climate projections suggest may become more frequent and severe.
The name Koto, selected to replace the destructive Typhoon Kammuri from earlier lists, served its purpose. It reminded the world that the fury of a storm is not measured by wind speed alone. The persistent, harp-string pluck of heavy rain on landscapes and livelihoods can orchestrate a disaster all its own. The journey of Typhoon Koto from a tropical depression near Palau to a flood-bringer in Vietnam stands as a critical case study in resilience, preparedness, and the evolving nature of tropical cyclones in a changing world.