The island of Nangan is not only the largest island of its township, but also the largest island of Matsu. Nangan Township is also the largest township in Lienchiang County, with a population of about 4,000. The highest point of the island is the Yuntai Mountain peak at 250m. Nangan's climate is classified as subtropical, with distinct seasons. The average year-round temperature is 20C, with July and August reaching 34C and January temperatures as low as 1.8C. There is an intense fog period during March and April which often affects the scheduled flights at Nangan Airport.