August in Scottsdale is the rainiest month of the year. In August, the weather in Scottsdale is typically hot. Average daily high temperature in August is about 38 degrees above zero. On average, Scottsdale has 19 sunny, 7 partly cloudy, and 5 rainy days in August. The rains are usually light. August as well as June and July is considered the most uncomfortable time to visit Scottsdale.