July in Cheonan is the rainiest, the cloudiest, and the warmest month of the year. In July, the weather in Cheonan is typically hot. Average daily high temperature in July is about 27 degrees above zero. On average, Cheonan has 25 rainy, 5 sunny, and 1 cloudy day in July. The rains are usually heavy. July as well as August is considered the most uncomfortable time to visit Cheonan.