August in Kirkwall is the warmest month of the year. In August, the weather in Kirkwall is typically warm. Average daily high temperature in August is about 14 degrees above zero. On average, Kirkwall has 18 rainy, 5 sunny, 5 cloudy, and 3 partly cloudy days in August. The rains are usually moderate. August as well as January, February, March, and April is considered the most uncomfortable time to visit Kirkwall.