May in Kirkwall is the sunniest month of the year. In May, the weather in Kirkwall is typically warm. Average daily high temperature in May is about 10 degrees above zero. On average, Kirkwall has 17 rainy, 7 sunny, 6 partly cloudy, and 1 cloudy day in May. The rains are usually moderate. May as well as January, February, March, and April is considered the most uncomfortable time to visit Kirkwall.