December in Big Bear Lake is the coldest month of the year. In December, the weather in Big Bear Lake is typically warm. Average daily high temperature in December is about 10 degrees above zero. On average, Big Bear Lake has 14 sunny, 12 partly cloudy, 4 rainy, and 1 cloudy day in December. The rains are usually light. December as well as January and February is considered the most uncomfortable time to visit Big Bear Lake.