December in Kostanai is the windiest month of the year. In December, the weather in Kostanai is typically freezing. Average daily high temperature in December is about 10 degrees below zero. On average, Kostanai has 16 cloudy, 5 snowy, 5 sunny, and 5 partly cloudy days in December. The snowfalls are usually light. December as well as January and February is considered the most uncomfortable time to visit Kostanai.