July in Grapevine is the hottest month of the year. In July, the weather in Grapevine is typically hot. Average daily high temperature in July is about 34 degrees above zero. On average, Grapevine has 23 sunny, 6 partly cloudy, and 2 rainy days in July. The rains are usually light. July as well as January, August, and December is considered the most uncomfortable time to visit Grapevine.