January weather forecast in Petaluma

January in Petaluma is the rainiest month of the year. In January, the weather in Petaluma is typically warm. Average daily high temperature in January is about 13 degrees above zero. On average, Petaluma has 12 sunny, 12 partly cloudy, and 7 rainy days in January. The rains are usually heavy. January as well as February and December is considered the most uncomfortable time to visit Petaluma.