January in Triest is the coldest month of the year. In January, the weather in Triest is typically cold. Average daily high temperature in January is about 5 degrees above zero. On average, Triest has 11 rainy, 9 sunny, 7 partly cloudy, and 4 cloudy days in January. The rains are usually heavy. January as well as February, November, and December is considered the most uncomfortable time to visit Triest.