Roosevelt High School’s website has a great list of many summer opportunities which is updated every month from December to June. Check it out here: http://roosevelths.seattleschools.org/UserFiles/Servers/Server_7419/File/2018%20Summer%20Bulletin%20Dec%202017.pdf
Also see the Summer Program Finder, a way to search for summer programs: www.SummerProgramFinder.com
www.TeenLife.com is a dedicated search engine for enrichment opportunities exclusively for teens. Nearly 15,000 summer, gap, and community service options in the U. S. and abroad are listed.