January in Slak is the most freezing month of the year. In January, the weather in Slak is typically freezing. Average daily high temperature in January is about 11 degrees below zero. On average, Slak has 20 cloudy, 7 snowy, and 4 sunny days in January. The snowfalls are usually light. January as well as February, April, October, and December is considered the most uncomfortable time to visit Slak.