May in Cavan is the sunniest month of the year. In May, the weather in Cavan is typically warm. Average daily high temperature in May is about 13 degrees above zero. On average, Cavan has 25 rainy, 5 sunny, and 1 partly cloudy day in May. The rains are usually moderate. May as well as January, February, March, and April is considered the most uncomfortable time to visit Cavan.