In August, the weather in Berwick-upon-Tweed is typically warm. Average daily high temperature in August is about 16 degrees above zero. On average, Berwick-upon-Tweed has 20 rainy, 4 sunny, 4 cloudy, and 3 partly cloudy days in August. The rains are usually moderate. August as well as January, February, May, and June is considered the most uncomfortable time to visit Berwick-upon-Tweed.