January in Osaka is the coldest month of the year. In January, the weather in Osaka is typically cold. Average daily high temperature in January is about 7 degrees above zero. On average, Osaka has 13 partly cloudy, 9 sunny, 7 rainy, and 2 cloudy days in January. The rains are usually light. January as well as February, March, June, and July is considered the most uncomfortable time to visit Osaka.