August in Mukilteo is the warmest month of the year. In August, the weather in Mukilteo is typically warm. Average daily high temperature in August is about 22 degrees above zero. On average, Mukilteo has 18 sunny, 11 partly cloudy, and 2 rainy days in August. The rains are usually light. August as well as July is considered the most comfortable time to visit Mukilteo.