May in Omagh is the sunniest month of the year. In May, the weather in Omagh is typically warm. Average daily high temperature in May is about 12 degrees above zero. On average, Omagh has 23 rainy, 5 sunny, and 3 cloudy days in May. The rains are usually moderate. May as well as January, February, March, and April is considered the most uncomfortable time to visit Omagh.