December in Nagasaki is the windiest month of the year. In December, the weather in Nagasaki is typically warm. Average daily high temperature in December is about 11 degrees above zero. On average, Nagasaki has 16 rainy, 7 sunny, 5 partly cloudy, and 3 cloudy days in December. The rains are usually heavy. December as well as January, February, June, and July is considered the most uncomfortable time to visit Nagasaki.