January in Zion National Park is the rainiest month of the year. In January, the weather in Zion National Park is typically cold. Average daily high temperature in January is about 6 degrees above zero. On average, Zion National Park has 18 sunny, 9 partly cloudy, and 4 rainy days in January. The rains are usually light. January as well as February and December is considered the most uncomfortable time to visit Zion National Park.