January in Sligo is the windiest, the cloudiest, and the coldest month of the year. In January, the weather in Sligo is typically cold. Average daily high temperature in January is about 6 degrees above zero. On average, Sligo has 27 rainy, 2 sunny, and 2 cloudy days in January. The rains are usually heavy. January as well as February, March, April, and May is considered the most uncomfortable time to visit Sligo.