Yes, folks, summertime music is sounding from monuments to memorials all around the city. Beginning Friday at the Jefferson Memorial, the United States Air Force Band will perform for its season opener the classics of Rossini, Vivaldi and Verdi, and the Singing Sergeants will bring their new multi-media production, "America's Reach for the Skies," starting at 8. You can catch the Air Force band at the memorial every Friday night throughout the summer and on Tuesday evenings on the Capitol's west terrace at 8. All the concerts are free. Call 767-5658. * The United States Navy Band also has a free concert series. On Friday the Commodores, the Navy's jazz ensemble, will play at the National Air and Space Museum, Seventh and Independence SW, at noon. On Saturday, the Commodores sail over to Waterfront Park in Alexandria for another noontime performance. The Navy's bands play every Monday evening at 8 on the west terrace of the Capitol, Wednesdays at noon at the National Museum of American History (14th and Constitution NW) and Thursday nights at 8:30 at the Jefferson Memorial. Call 433-2394. * Completing the summer series list at the Jefferson Memorial are the United States Army Band every Tuesday at 8 and the United States Marine Band on Sundays at 8:30. Georgetowns canal concerts commence Sunday 1:30 to 4:30 in front of The Foundry Mall alongside the C&O Canal in Georgetown. This season's musical entertainment will feature everything from jazz to classical to big-band to folk tunes. The first free concert has a bit of Irish flavor with the local band Celtic Thunder and the Peggy O'Neill dancers. Later the same afternoon, the Toni Wilson Quartet takes the stage with some hot-jazz numbers. Also appearing this summer are: Blue Mountain (acoustic country), the Trinidad Steel Band (Caribbean rhythms) and the Crystal Strings Quartet (classical pops). The concerts will continue every other Sunday until September 11. If it rains, the program will be held inside the mall. The Foundry Mall is between 30th and Thomas Jefferson streets NW -- just below M Street in Georgetown.The summer outdoor concert series runs through August 30; no tickets are required. Call 426-6700 for a complete schedule