August in Kostomucsha is the rainiest month of the year. In August, the weather in Kostomucsha is typically warm. Average daily high temperature in August is about 16 degrees above zero. On average, Kostomucsha has 20 rainy, 6 sunny, 4 partly cloudy, and 1 cloudy day in August. The rains are usually moderate. August as well as January, April, May, and June is considered the most uncomfortable time to visit Kostomucsha.