January in Dublin is the coldest month of the year. In January, the weather in Dublin is typically cold. Average daily high temperature in January is about 7 degrees above zero. On average, Dublin has 12 rainy, 9 partly cloudy, 8 cloudy, and 2 sunny days in January. The rains are usually moderate. January as well as February, March, April, and May is considered the most uncomfortable time to visit Dublin.