Hit by the nationwide slump in the housing market, the fallout from high interest rates and rising unemployment, metropolitan Washington's economy heads into the final months of the year with more soft spots than usual.

Much the same is true throughout Maryland and Virginia, where business and government leaders, while appearing optimistic about the final quarter, say there is a great deal of uncertainty. A good deal of that uncertainty, they point out, is rooted in questions about the eventual impact of Reagan administration economic policies.

"As far as the rest of the year is concerned, I still see some slowness in the (state's) economy," said Dr. Leland E. Traywick, director of the bureau of business research at The College of William and Mary in Williamsburg.

Traywick believes the slowdown in Virginia's economy will continue through October and "pick up toward the end of the year."

In Maryland, uncertainty is "the dominant theme" not only for the state but for the entire nation, observed Padraic Frucht, director of research for Maryland's department of economic and community development.

"We're sort of on a thin edge," said Frucht. "I think a lot depends on the tax cut that begins in October. The tax cuts will be trivial but the budget cuts will affect a lot of people."

Locally, uncertainty is also the operative word in any assessment of the economy by business and government officials as they approach the final quarter of the current year and early 1982.

But while acknowledging that unemployment and stubbornly high interest rates pose some bothersome problems, most businessmen in the area remain confident that the underlying economy here is still strong and that it will resume growth at a moderate pace.

"If rates decline and stabilize, this economy will go gangbusters," predicted Stephen Harlan, managing partner of the Washington office of Peat Marwick & Mitchell Co. and president-elect of the Greater Washington Board of Trade.

But for now, noted Harlan, small retailers and financial institutions, particularly the savings and loans, "are having a tough time" as a result of high interest rates.

"I think the local economy is somewhat flat," declared Sheldon W. Fantle, president and chief executive officer of Peoples Drug Stores Inc.

"Much of the local economy is tied to real estate, and with interest rates what they are today, there's less building going on," observed Fantle.

Businessmen "recognize that volume won't be as high, so we're going to have to cut down on our overhead," he added.

In the District, where economic growth, except in a very few sectors, has proceeded at a relatively slow pace over the last decade, the outlook is optimistic despite concern over the impact of high interest rates and the specter of higher unemployment.

Despite what he called a "tremendous amount of uncertainty," over reductions in federal employment, most sectors of the local economy should remain fairly stable through the end of the year, said James E. Cotter, district staff manager for economics at the C&P Telephone Companies.

Although acknowledging that there has been a big downturn in the housing industry, due largely to high interest rates, Cotter said the private sector is still "fairly strong."

The strength of that sector is found primarily in the retail trade and services areas. "Both are slowing down but they aren't in trouble," Cotter said.

Cotter sees moderate growth for the local economy through the remaining months of this year.

On the other hand, he said, "We expect very little growth in local government. They've lost federal funds, especially CETA Comprehensive Employment Training Act money. From now on, I think we'll see local governments with their traditional moderate growth."

The near-term outlook for the District can be described as optimistic, said a financial economist in the city's department of finance and revenue.

Despite his optimism, however, the same economist worried about the potential consequences of continuing high interest rates and a cut in federal employment.

And although the District is "still fairly strong economically," in the opinion of the finance department economist, he acknowledged that "unemployment right now is looking very bad, and that's worrisome."

A key to the employment picture is how well the city -- the entire metropolitan area, for that matter -- will be able to absorb the loss of 4,000 to 5,000 federal jobs.

On the other hand, the District has been adjusting, over the past year at least, to a gradual decrease in government employment. Between May 1980 and May 1981, the number of District government jobs declined by 4,000. In the same 12-month period, there was a decrease of 4,300 federal jobs.

Meanwhile, District officials are becoming increasingly concerned over the latest unemployment figures, which boosted the rate to 10.2 percent, reversing an 18-month downward trend.

D.C. Mayor Marion Barry Jr. attributed the higher rate largely to cuts in federal agency jobs and "the accompanying impact on the private sector, as well as the national state of the economy."

The loss of jobs, perhaps as many as 2,000 by the end of the year, according to estimates developed in the District's finance and revenue office, will have an effect on retail sales, officials believe.

Retailers as well as the city's financial experts agree that retail sales won't be helped very much by the 4.8 percent pay increase that has been approved for federal white-collar workers. They agree, however, that retail sales "will continue fairly strong into the next year."

"So far, our sales tax revenues have been above estimates," said an official in the finance and revenue office. "I'd say say (retail sales) have kept pace with inflation, maybe a little better. They're probably going to be a cent or a cent and a half below inflation next year."

The services sector, now the second largest in the local economy, continues to be the "bright spot," among indicators, say District officials. Employment in that sector increased by 3,700, or 22 percent, during a 12-month period ended May 30.

Strong demand for space and the completion of 2.5 million square feet already this year qualify office building construction as another bright spot in the region's economy. Although commercial building activity has slowed in Washington's suburbs this year, developers are proceeding at a record pace in the District, which would produce almost 11 million square feet of space between 1982 and 1984.

"The commercial real estate market is a barometer of business optimism and near-term vitality of the area," said James B. O'Brien, vice president and resident manager of Coldwell Banker's Washington office.

But while office building construction continues at a boom pace in downtown Washington, the supply of new space in Northern Virginia has declined slightly. Some softness has occurred in suburban Maryland as well.

For government officials in the various county jurisdictions, construction of much-needed capital projects is of greater concern. In recent testimony before a congressional subcommittee, for example, officials from Montgomery and Prince George's counties complained that soaring interest rates have made it increasingly difficult for them to float bond issues.

"The county is reviewing its capital projects in light of high interest rates," an official in the Montgomery County office of finance confirmed in a recent interview.

Dan Lucas, assistant director of that office, acknowledged that "there are going to be some soft spots," but he said county officials "anticipate a bright future even though interest rates are still high."

Despite a slowdown throughout the area, new construction has "held up well," in the county, said Lucas. And, while growth of the labor force has slowed somewhat, the unemployment rate in the county fell to 3.9 percent in July, compared with 7.3 percent a year earlier.

For the entire metropolitan area, the unemployment rate remained unchanged at 5.4 percent in July, the latest month for which figures are available.

Nonetheless, a labor market analysis prepared by the D.C. Department of Employment Services underscored the uncertainties that could change that rate significantly. This uncertainty is attributable to two factors: the net impact of the Reagan administration's budget cuts and the ability of the private sector to absorb government employes affected by those cuts.