In mid-May, the Return of the Orcas Festival (360/378-5240) brings kayak races, art booths, children’s games, and music to Roche Harbor [1]. A popular Summer Arts Fair on the third weekend of July includes art exhibits, food booths, and live music.
The 4th of July brings a variety of fun events, including a parade, pig barbecue contests with celebrity judges, a 10K race, music, dancing, and evening fireworks over Friday Harbor. (The best local 4th of July fireworks, however, are over at Roche Harbor Village.)
The four-day San Juan County Fair (360/378-4310, www.sanjuancountyfair.org [2]) in mid-August features a sheep-to-shawl race, chicken and rabbit races, music, livestock judging, and, of course, carnival rides.
Each Memorial Day, Friday Harbor has a popular parade with speeches.
Oktoberfest comes to the fairgrounds in early October, with polka music and dancing, along with German beer and food.
Links:
[1] http://www.moon.com/destinations/washington/san-juan-islands/san-juan-island/sights/roche-harbor
[2] http://www.sanjuancountyfair.org