<p>The southern Taiwan Strait is inhabited by a large amount of coral reef, but experienced the largest sea surface temperature (SST) variability in winter along the China coast. The strait often suffers extremely cold event with an increasing frequency in the recent decades. The SST falls as low as 14&#xa0;°C during the extremely cold event which threatens the survival of coral reef and fish, the economically highly-prized grey mullet (<i>Mugil cephalus L.</i>) for example. The unclear relationship between the local extremely cold event and large-scale climate variability (El Niño-Southern Oscillation, ENSO, and Pacific Decadal Oscillation, PDO) and growing global warming still confound our understanding and prediction of the extremely cold event. With the Singular Value Decomposition (SVD) method, we find that the ENSO and PDO could drive the cold event in a specific phase combination that is a strong La Niña in conjunction with a negative PDO phase. The strong La Niña can largely strengthen the local northeasterly wind through the low-level cyclone over East Asia and further intensify the China Coastal Current which transport large amount of cold water to the coral reef area in the Taiwan Strait. In the La Niña year of the negative PDO phase, the cyclone over East Asia is able to develop with weak influence from Aleutian Low which moves to the northeastern corner in the North Pacific Ocean. However, in the La Niña year of the positive PDO phase, the La Niña influence is suppressed to the tropical Pacific Ocean and only drive a weak influence on the local wind in the Taiwan Strait as the Aleutian Low occupies the entire North Pacific Ocean. This mechanism is validated by the numerical models and could well explain the increasing frequency of cold event in the recent decade.</p>