July in Arrochar is the rainiest and the warmest month of the year. In July, the weather in Arrochar is typically warm. Average daily high temperature in July is about 15 degrees above zero. On average, Arrochar has 29 rainy and 2 sunny 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 Arrochar.