In May, the weather in Bol'shiye Syry is typically warm. Average daily high temperature in May is about 14 degrees above zero. On average, Bol'shiye Syry has 14 rainy, 8 partly cloudy, 5 cloudy, and 4 sunny days in May. The rains are usually moderate. May as well as January, February, September, and October is considered the most uncomfortable time to visit Bol'shiye Syry.