April in Rock Springs is the rainiest month of the year. In April, the weather in Rock Springs is typically cold. Average daily high temperature in April is about 9 degrees above zero. On average, Rock Springs has 13 rainy, 8 partly cloudy, 7 sunny, and 2 cloudy days in April. The rains are usually moderate. April as well as March and May is considered the most uncomfortable time to visit Rock Springs.