December in Klamath Falls is the snowiest and the coldest month of the year. In December, the weather in Klamath Falls is typically cold. Average daily high temperature in December is about 2 degrees above zero. On average, Klamath Falls has 9 rainy, 7 partly cloudy, 6 sunny, 6 cloudy, and 3 snowy days in December. The rains are usually moderate. December as well as January, February, March, and November is considered the most uncomfortable time to visit Klamath Falls.