January in Thessaloniki is the coldest month of the year. In January, the weather in Thessaloniki is typically cold. Average daily high temperature in January is about 9 degrees above zero. On average, Thessaloniki has 12 sunny, 7 rainy, 7 partly cloudy, and 5 cloudy days in January. The rains are usually moderate. January as well as February and December is considered the most uncomfortable time to visit Thessaloniki.