April in Harbour Island is the sunniest month of the year. In April, the weather in Harbour Island is typically warm. Average daily high temperature in April is about 24 degrees above zero. On average, Harbour Island has 26 sunny, 3 rainy, and 1 partly cloudy day in April. The rains are usually light. April as well as January, February, March, and May is considered the most comfortable time to visit Harbour Island.