May in Sligo is the sunniest month of the year. In May, the weather in Sligo is typically warm. Average daily high temperature in May is about 13 degrees above zero. On average, Sligo has 24 rainy, 5 sunny, 1 cloudy, and 1 partly cloudy day in May. The rains are usually heavy. May as well as January, February, March, and April is considered the most uncomfortable time to visit Sligo.