January in Hermiston is the cloudiest month of the year. In January, the weather in Hermiston is typically cold. Average daily high temperature in January is about 3 degrees above zero. On average, Hermiston has 21 cloudy, 6 rainy, 3 sunny, and 1 partly cloudy day in January. The rains are usually light. January as well as March and December is considered the most uncomfortable time to visit Hermiston.