April in Casper is the rainiest and the cloudiest month of the year. In April, the weather in Casper is typically warm. Average daily high temperature in April is about 10 degrees above zero. On average, Casper has 13 partly cloudy, 9 sunny, and 8 rainy days in April. The rains are usually light. April as well as February, March, and November is considered the most uncomfortable time to visit Casper.