After 15 consecutive days of temperatures below 90, it has suddenly turned hot here again, as Sunday's high of 90 degrees was followed yesterday by a steamy 90.

In the wake of a steady run up of the mercury, from 78 on Thursday, through 79 on Friday and 87 on Saturday, weather forecasters say they expect August will close in a blaze of late summer disagreeability, with sultry, sticky days in prospect from now through the first two days of September.

In technical terms, explained National Weather Service forecaster Harold Hell, "we're getting back to a southerly flow."

That means the breezes prevailing here are coming from South Atlantic and Gulf Coast regions long famed as producers and purveyors of heat and humidity.

"High temperatures probably will be well up in the 80s or around 90 for the balance of the week," Hess said.

Although there is a chance of scattered thundershowers "here and there" each afternoon and evening, the forecaster added, the chance is "very slight" and most areas will get no rain.

On the sunbaked downtown streets, shirtsleeved noontime strollers greeted each other with good-natured grimaces in their bond of shared suffering.

"Mad dogs and Englishmen!" a man on L. Street NW exclaimed to an approaching acquaintance, in wry reference to the only categories of creatures expected to venture forth in the noonday sun of such days as yesterday.

Although altruists might more easily bear the burdens of the heat in the recognition that some individuals are actually helped by it, it appeared that these individuals may not include out-door ice cream salesmen.

"If it's too hot, they don't buy it," vendor Pete Jenkins said of the ice cream he was trying to sell at 10th Street and Constitution Avenue NW. "It (the hot weather) kills ice cream," he said.

While many Washingtonians for all too obvious reasons make it a point not to be here in August, travelers and tourists are always arriving.

Bill Sorensen, who described himself as a continuing student, stopped off here to visit a friend while returning to California from a year in Europe.

"This is the hottest weather I've come across in all my journeying," he told a reporter on G Street NW.

The forecast for today calls for sunny warm and humid weather with high temperatures from 88 to 92 degrees.