In April, the weather in North Sioux City is typically warm. Average daily high temperature in April is about 14 degrees above zero. On average, North Sioux City has 11 partly cloudy, 10 rainy, 8 sunny, and 1 cloudy day in April. The rains are usually moderate. April as well as February, March, November, and December is considered the most uncomfortable time to visit North Sioux City.