August is Washington's informal tribute to Marilyn Monroe: the asphalt jungle. Women (and baggy-trousered men) pause over subway vents for a brief rush of cool air, bus stops are populated by heavy-lidded pouters, and ice -- the old slang for diamonds -- is still a girl's best friend.

Some even like it hot: Pepco's figures indicated that area residents used less electricity yesterday than on Wednesday, even though it was warmer.

National Airport reached an official high of 98 degrees shortly before 5 p.m., breaking the 1947 record of 96 degrees. For the second day in a row, Dulles Airport survived a near brush with the murderous mercury, slipping in at just under 100 degrees.

National Weather Service forecasters held little hope for relief, predicting overnight temperatures in the 70s with increasing humidity levels as the evening comes on.

"In other words, it gets cooler but stickier after dark," as one forecaster put it.

Highs today are expected to return to the 90s and, along with the increasing humidity, there will be a 40 percent possibility of showers and thunderstorms. Meteorologists warn that this classical summer air -- comprising the three H's: haze, heat and humidity -- will linger through Saturday, at least.

Meanwhile, Washingtonians are flocking to the town's cooler spots: shopping malls, movie houses and the Metro. The subway, while it offers only a modicum of scenery, has become one of the area's heat-wave hangouts. Recently, according to Metro figures, ridership has been rising along with the temperature readings: up to 444,000 a day from a weekday average of 406,000 a month ago.

"The stations are air-conditioned and the trains are air-conditioned," Metro spokesman Marilyn Dicus pointed out. "So long as you don't eat or play the radio or carry an animal with you, you could ride around for, like, three hours, if that's your idea of cool. You could even read, if your stomach will take it."

And the subterranean vacation is cheap.

"If you get on and off at the same station in non-rush hour, it's only 80 cents," Dicus said.

Now that teen-agers hereabouts have taken to parading their underground punk wear, window The subway . . . . has become one of the area's heat-wave hangouts. shopping in the subway has become a walk on the wild ride.

"Do you think I'd look good as a blonde?" a high-heeled businesswoman under Farragut Square asked her male companion, staring thoughtfully at a bleached Mohawk haircut.

Although the days gradually are getting shorter, there still are 13 2/3 hours of smeary sunlight in each 24. And besides the heat and high dew point, there are those eye, ear, nose and throat specialties: ozone levels in the moderate-to-high range (rated a "moderate" 100 Thursday) and, in the past few days, the first late-summer ragweed sniffles.

But, after all, airborne vegetation is nothing new: The Saxons called August Woedmonath, "the weed month."