March in Portland is the rainiest month of the year. In March, the weather in Portland is typically warm. Average daily high temperature in March is about 13 degrees above zero. On average, Portland has 19 rainy, 6 partly cloudy, 4 sunny, and 2 cloudy days in March. The rains are usually heavy. March as well as January, February, April, and November is considered the most uncomfortable time to visit Portland.