Mount Vernon is a city in Skagit County, Washington, United States. The population was 31,743 at the 2010 census. It is one of two principal cities of and included in the Mount Vernon-Anacortes, Washington Metropolitan Statistical Area. It is the county seat of Skagit County. Downtown Mount Vernon is known for its annual Tulip Festival Street Fair which is part of the Skagit Valley Tulip Festival. The climate of Skagit County is similar to that of northern France.