December in Sendai is the rainiest month of the year. In December, the weather in Sendai is typically cold. Average daily high temperature in December is about 5 degrees above zero. On average, Sendai has 21 rainy, 4 sunny, 4 cloudy, and 2 partly cloudy days in December. The rains are usually moderate. December as well as January, February, and March is considered the most uncomfortable time to visit Sendai.