December in Aberystwyth is the windiest and the cloudiest month of the year. In December, the weather in Aberystwyth is typically cold. Average daily high temperature in December is about 7 degrees above zero. On average, Aberystwyth has 24 rainy, 4 sunny, 2 cloudy, and 1 partly cloudy day in December. The rains are usually heavy. December as well as January, February, May, and July is considered the most uncomfortable time to visit Aberystwyth.