August in Terrance B. Lettsome International Airport is the hottest month of the year. In August, the weather in Terrance B. Lettsome International Airport is typically hot. Average daily high temperature in August is about 29 degrees above zero. On average, Terrance B. Lettsome International Airport has 20 sunny, 9 rainy, and 2 partly cloudy days in August. The rains are usually moderate.