July in Dinan is the warmest month of the year. In July, the weather in Dinan is typically warm. Average daily high temperature in July is about 20 degrees above zero. On average, Dinan has 14 partly cloudy, 9 sunny, 7 rainy, and 1 cloudy day in July. The rains are usually light. July as well as June and August is considered the most comfortable time to visit Dinan.