In April, the weather in Harstad is typically cold. Average daily high temperature in April is about 2 degrees above zero. On average, Harstad has 20 rainy, 6 sunny, 2 partly cloudy, 1 snowy, and 1 cloudy day in April. The rains are usually heavy. April as well as March, May, June, and July is considered the most uncomfortable time to visit Harstad.