December in Austin is the cloudiest month of the year. In December, the weather in Austin is typically warm. Average daily high temperature in December is about 14 degrees above zero. On average, Austin has 13 partly cloudy, 11 sunny, 5 rainy, and 2 cloudy days in December. The rains are usually light. December as well as January, May, June, and July is considered the most uncomfortable time to visit Austin.