December in Bialystok is the windiest month of the year. In December, the weather in Bialystok is typically cold. Average daily high temperature in December is about 1 degree above zero. On average, Bialystok has 16 cloudy, 9 rainy, 5 snowy, and 1 sunny day in December. The rains are usually moderate. December as well as March, April, and November is considered the most uncomfortable time to visit Bialystok.