August in Gig Harbor is the warmest month of the year. In August, the weather in Gig Harbor is typically warm. Average daily high temperature in August is about 25 degrees above zero. On average, Gig Harbor has 24 sunny, 6 partly cloudy, and 1 rainy day in August. The rains are usually light. August as well as July and September is considered the most comfortable time to visit Gig Harbor.