Hot town, summer in the city. Notice the lull? With the tourists sticking to monumental routes and everyone else on leave, we're all alone. Now's the time to get a trim, nab a fox, do figure eights or see "To Fly."

"They've all gone to the beach," said barber Donato Casarella last Saturday, comforting his three partners who stood idly waiting for the shaggy in a Riverdale shop. "They'll come back in September when the kids have to be in school."

Some retreats are still going strong: Park attendants at Lake Fairfax and Burke Lake in Virginia say the pools are busy as ever, and Bob's Famous Homemade Ice Cream reports "we're at the peak of our season." But they're the exceptions that prove the trend.

At the National Gallery East Building, for example, "El Greco" empties out at 8:30 weeknights and the Air & Space Museum, also open until 9, reports that its last showing of "To Fly," at 8:15 daily, has been only half-filled. Even the queue for "E.T." has dwindled in these dog days. Evelyn Jayson, spokeswoman for K-B Theaters, says the flick, now in its tenth week, draws no lines in mid-week and no longer sells out on weekends.

The avenues are passable (excepting Wisconsin and M at the height of the weekend) and empty legal parking places have been sighted in the thick of Georgetown. Restaurants and shops there are sleepy until about 9:30 p.m., when Virginia and Maryland tags arrive on the scene. A line may form at the Third Edition but other watering holes serve pints without a wait. (The only obvious throng is at the Key Theater, where the Rocky Horror Picture Show attracts its usual unusual crowd. Saturday night, tickets for the comedy-horror flick were sold out more than an hour before showtime.)

But August means Saturday dinners are possible without a reservation at Mel Krupin's. "It's been very slow on weekends," says Mel's secretary Barbara Helsley, "and that's how it will be through this week," although the restaurant gives in to the doldrums Monday, closing through August 30.

There's a crowd at the trashy summer- reading racks at Crown Books on K Street, but only during weekday lunch hours. On Saturday the gothics, mysteries, sci-fi thrillers and self-helpers go begging. Shrimp prices are at a seasonal low at Maine Avenue's stands (mediums are $5.99 a pound) and vendors shout for business.

Glen Echo Park off MacArthur Boulevard in Maryland is pleasantly quiet. The kids' carousel whirls with no wait for tickets; picnic tables are vacant, exhibits and amusement building relics are lonesome. An attendant at Palisades Recreation Center at Sherrier Street and Dana Place NW says there's been a drop in tennis court sign-ups "because everyone is traveling."

Schizophrenia at Bloomingdale's: the bathing suit/winter coat department at White Flint tilts toward winter, but you may still pick up a $56 swimsuit for $12.95. Depending on your animal instincts, it's fur season. Gartenhaus in Bethesda is offering a 20 percent dog-days discount on the new collection. (Mink still leads the pack.) Vicarious chill: Ski Chalet in Arlington and Ski Center off Massachusetts Avenue NW both begin annual summer sales this week to make room for next year's skis, boots and whatnot. Get a jump on the season by scheduling equipment tune-ups while most jocks are still water-skiing.

Cool your heels at Mount Vernon District Park Ice Rink, where you'll circle the ice with only 20 or 30 other freaks. The crowd triples on Saturday nights in December. "Now you have the place to yourself," promises snackbar attendant Lynda Neas. The hours will be extended starting Saturday.