July in Belfast is the warmest month of the year. In July, the weather in Belfast is typically warm. Average daily high temperature in July is about 16 degrees above zero. On average, Belfast has 22 rainy, 5 sunny, 2 cloudy, and 2 partly cloudy days in July. The rains are usually heavy. July as well as January, February, March, and April is considered the most uncomfortable time to visit Belfast.