January in San Jose is the windiest, the cloudiest, and the coldest month of the year. In January, the weather in San Jose is typically warm. Average daily high temperature in January is about 26 degrees above zero. On average, San Jose has 29 rainy, 1 cloudy, and 1 partly cloudy day in January. The rains are usually heavy. January as well as February, March, April, and May is considered the most uncomfortable time to visit San Jose.