In September, the weather in Demänovska Dolina is typically warm. Average daily high temperature in September is about 16 degrees above zero. On average, Demänovska Dolina has 13 rainy, 6 sunny, 6 partly cloudy, and 5 cloudy days in September. The rains are usually heavy. September as well as February, March, April, and May is considered the most uncomfortable time to visit Demänovska Dolina.