May in Karlovy Vary is the rainiest month of the year. In May, the weather in Karlovy Vary is typically warm. Average daily high temperature in May is about 15 degrees above zero. On average, Karlovy Vary has 18 rainy, 7 sunny, 3 cloudy, and 3 partly cloudy days in May. The rains are usually moderate. May as well as March, April, November, and December is considered the most uncomfortable time to visit Karlovy Vary.