March in Seattle is the rainiest month of the year. In March, the weather in Seattle is typically warm. Average daily high temperature in March is about 10 degrees above zero. On average, Seattle has 19 rainy, 7 partly cloudy, 4 sunny, and 1 cloudy day in March. The rains are usually heavy. March as well as January, February, April, and October is considered the most uncomfortable time to visit Seattle.