April in Belfast is the sunniest month of the year. In April, the weather in Belfast is typically warm. Average daily high temperature in April is about 10 degrees above zero. On average, Belfast has 12 rainy, 8 cloudy, 6 sunny, and 4 partly cloudy days in April. The rains are usually light. April as well as January, February, March, and May is considered the most uncomfortable time to visit Belfast.