January in Harbour Island is the coldest month of the year. In January, the weather in Harbour Island is typically warm. Average daily high temperature in January is about 23 degrees above zero. On average, Harbour Island has 20 sunny, 9 partly cloudy, and 2 rainy days in January. The rains are usually light. January as well as February, March, April, and May is considered the most comfortable time to visit Harbour Island.