August in Altoona is the sunniest month of the year. In August, the weather in Altoona is typically warm. Average daily high temperature in August is about 24 degrees above zero. On average, Altoona has 19 sunny, 6 rainy, and 6 partly cloudy days in August. The rains are usually moderate. August as well as July is considered the most comfortable time to visit Altoona.