April in Ishim is the rainiest month of the year. In April, the weather in Ishim is typically cold. Average daily high temperature in April is about 7 degrees above zero. On average, Ishim has 17 cloudy, 10 rainy, 2 sunny, and 1 partly cloudy day in April. The rains are usually light. April as well as January, February, October, and December is considered the most uncomfortable time to visit Ishim.