May in Kalach-na-Donu is the rainiest month of the year. In May, the weather in Kalach-na-Donu is typically warm. Average daily high temperature in May is about 21 degrees above zero. On average, Kalach-na-Donu has 12 sunny, 11 rainy, 7 partly cloudy, and 1 cloudy day in May. The rains are usually light.