January in Ljubljana is the coldest month of the year. In January, the weather in Ljubljana is typically cold. Average daily high temperature in January is about 2 degrees above zero. On average, Ljubljana has 10 rainy, 9 cloudy, 6 sunny, and 6 partly cloudy days in January. The rains are usually heavy. January as well as February, March, November, and December is considered the most uncomfortable time to visit Ljubljana.