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