July in Merriam is the hottest month of the year. In July, the weather in Merriam is typically hot. Average daily high temperature in July is about 31 degrees above zero. On average, Merriam has 14 sunny, 9 rainy, 7 partly cloudy, and 1 cloudy day in July. The rains are usually heavy. July as well as January, February, March, and June is considered the most uncomfortable time to visit Merriam.