December in Kushiro is the windiest and the sunniest month of the year. In December, the weather in Kushiro is typically cold. Average daily high temperature in December is about 1 degree above zero. On average, Kushiro has 16 sunny, 10 partly cloudy, 4 rainy, and 1 snowy day in December. The rains are usually heavy. December as well as March, April, June, and August is considered the most uncomfortable time to visit Kushiro.