August in Cavan is the cloudiest month of the year. In August, the weather in Cavan is typically warm. Average daily high temperature in August is about 15 degrees above zero. On average, Cavan has 29 rainy, 1 sunny, and 1 cloudy day in August. The rains are usually heavy. August as well as January, February, March, and April is considered the most uncomfortable time to visit Cavan.