August in Aberystwyth is the warmest month of the year. In August, the weather in Aberystwyth is typically warm. Average daily high temperature in August is about 17 degrees above zero. On average, Aberystwyth has 19 rainy, 7 partly cloudy, 3 sunny, and 2 cloudy days in August. The rains are usually heavy. August as well as January, February, March, and April is considered the most uncomfortable time to visit Aberystwyth.