January in Omagh is the windiest and the coldest month of the year. In January, the weather in Omagh is typically cold. Average daily high temperature in January is about 5 degrees above zero. On average, Omagh has 24 rainy, 3 sunny, 3 cloudy, and 1 partly cloudy day in January. The rains are usually heavy. January as well as February, March, April, and May is considered the most uncomfortable time to visit Omagh.