In December, the weather in Siheung is typically cold. Average daily high temperature in December is about 1 degree above zero. On average, Siheung has 14 sunny, 11 partly cloudy, 3 rainy, 2 cloudy, and 1 snowy day in December. The rains are usually moderate. December as well as February, July, and August is considered the most uncomfortable time to visit Siheung.