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 13 degrees above zero. On average, Kirkwall has 15 rainy, 8 partly cloudy, 6 cloudy, and 2 sunny days in August. The rains are usually heavy. August as well as January, February, March, and April is considered the most uncomfortable time to visit Kirkwall.