Explore new arias this weekend.WATCHFree Opera in the Outfield What: Washington National Opera simulcasts The Barber of Seville.Why: Cover your bases with a blanket. When: Sat., 7 p.m. Gates open at 5:30 p.m.Where: Nationals Park, 1500 Capitol St. SE, b/t N St. & Potomac Ave. Info at 202-572-3057.STRETCHSomaFit Fall Open HouseWhat: The swanky gym and spa offers gratis group exercise classes, skin care and massage demos, food, and gift bags.Why: It’s a free for fall.When: Sat., 9 a.m.-6 p.m.Where: 2121 Wisconsin Ave. NW, b/t Hall Pl. & 35th St. (202-965-2121).SCREENDC Shorts Film FestivalWhat: A week-long parade of domestic and international flicks for those with reel attention span issues.Why: Entertainment in short spurts.When: Thru Sept. 17.Where: Landmark’s E Street Cinema, 555 11th St. NW, entrance on E St. (202-452-7672); Burke Theater in the U.S. Navy Memorial, 701 Pennsylvania Ave. NW, b/t 7th & 8th Sts.SPENDD.C. Supports Fashion’s Night OutWhat: Boutiques extend their hours to celebrate with refreshments, music, and special guests.Why: You’ll be fashionably late.When: Today, ’til 11 p.m.Where: Find participating shops online at midcitylife.com.LISTENRosslyn Jazz FestivalWhat: Make jazz hands for free outdoor performances including the Spanish Harlem Orchestra.Why: Let the scat out of the bag.When: Sat., 12:30-7 p.m.Where: Gateway Park, 1300 Lee Hwy., Arlington (703-228-1850).GODailyCandy DossierWhat: All day, every day, we’ll be bringing you the latest and greatest from NY Fashion Week. Check back often for designer interviews, trend predictions, and front-row observances. Why: Giveaways galore. When: Thru Sept. 17.Where: Online at dailycandy.com/dossier.