February in Sliven is the cloudiest month of the year. In February, the weather in Sliven is typically cold. Average daily high temperature in February is about 5 degrees above zero. On average, Sliven has 11 cloudy, 8 partly cloudy, 6 sunny, and 4 rainy days in February. The rains are usually moderate. February as well as January, March, May, and December is considered the most uncomfortable time to visit Sliven.