January in Piracicaba is the rainiest and the cloudiest month of the year. In January, the weather in Piracicaba is typically warm. Average daily high temperature in January is about 27 degrees above zero. On average, Piracicaba has 27 rainy and 4 sunny days in January. The rains are usually heavy. January as well as February, March, November, and December is considered the most uncomfortable time to visit Piracicaba.