January in Ulsan is the sunniest and the coldest month of the year. In January, the weather in Ulsan is typically cold. Average daily high temperature in January is about 4 degrees above zero. On average, Ulsan has 25 sunny, 3 rainy, 2 partly cloudy, and 1 cloudy day in January. The rains are usually light. January as well as February, July, and August is considered the most uncomfortable time to visit Ulsan.