July in Plano is the hottest month of the year. In July, the weather in Plano is typically hot. Average daily high temperature in July is about 34 degrees above zero. On average, Plano has 22 sunny, 7 partly cloudy, and 2 rainy days in July. The rains are usually moderate. July as well as January, February, August, and December is considered the most uncomfortable time to visit Plano.