August in Leavenworth is the windiest and the warmest month of the year. In August, the weather in Leavenworth is typically warm. Average daily high temperature in August is about 22 degrees above zero. On average, Leavenworth has 21 sunny, 8 partly cloudy, and 2 rainy days in August. The rains are usually light. August as well as July is considered the most comfortable time to visit Leavenworth.