The summer months are usually so busy for the Largo Produce stand in Prince George's County that owner LaRista Carpenter hardly has time to take a five-minute break as she manages the tables of fruits and vegetables.

But these days, the produce has dwindled to a few tomatoes, a couple of baskets of cherries and some greens, all for nearly double the price of last year.

Carpenter picked up a cabbage the size of grapefruit and shook her head slowly. "These should be so much larger," she said.

The heat wave that has stifled the Washington area this month and the drought of the last several months are exacting their toll on area produce. As a result, local agricultural officials and retail grocers say consumers can expect to pay considerably higher prices for fruits and vegetables at roadside stands, and moderately higher prices in some grocery stores in the coming months.

Maryland and Virginia officials who track monthly prices of certain food items said prices this month are considerably higher than they were in July 1985. The increases are greater than the increase posted in the consumer price index for grocery items from May 1985 to May 1986, which was about 4.2 percent for the Washington area.

For instance, in Virginia, potatoes have gone up 30 percent, lettuce 45 percent and green beans 16 percent, according to Jan Hathcock of the Virginia Department of Labor and Industry. The price of cabbage has fallen 23 percent, she said.

Helen M. Huber, a marketing analyst for the Maryland Department of Agriculture, has figures showing that the price of potatoes has risen 23 percent, green beans have gone up 28 percent and cabbage is up 52 percent, while lettuce has stayed the same.

Both Hathcock and Huber said that comparing prices between regions is difficult because prices can fluctuate greatly from week to week.

Agriculture and grocery store officials are blaming higher prices on the extreme heat and drought for the higher prices. The Washington area has received only 12.38 inches of rain this year, about 8 inches less than normal for the period, according to National Weather Service spokesman Joseph Cefaratti.

The lack of rain, coupled with temperatures soaring into the 90s in the last two weeks during a critical growing time, has withered corn, burned soybeans and killed hundreds of thousands of chickens in farms along the Eastern Shore.

A handful of crops has gone unscathed. Ray Vaughn, deputy commissioner of the Virginia Agriculture Department in Richmond, is confident that peaches, for example, will be in good supply because they are harvested relatively early in the season. Although they might not be as large as they would be normally, "peaches can take the heat," he said.

Peanuts, which he said do not require a great deal of moisture, also are expected to do well in the coming weeks if the area receives at least some rain.

Nevertheless, "peanuts are showing some stress," he said. "Should we lose our peanut crop, you can look for some higher-priced peanut butter."

Grocery chains, such as Giant Food Inc. and Safeway Stores Inc., buy locally when produce is available, spokesmen said, although most of the buying is done from cooperatives in the South and Midwest.

"If a weather condition has affected the quality and quantity of vegetables and fruits in one area of the country, we are able to buy from other areas of the country," said Giant spokesman Barry Scher.

But it costs more to ship the fruits, and the transportation could cause a possible increase in prices for consumers, he added.

"Prices that normally come down at this time aren't," said Scher. He said prices normally decrease at this time of year because the market is usually glutted with a huge supply of fruits and vegetables -- but not so this year.

Safeway spokesman Larry Johnson also said that weather problems here and elsewhere have affected supply and could affect area prices. "Consumers are going to be experiencing a little bit higher costs," he said. Prices of peaches, nectarines, beans and corn are starting to rise, he said.

The Southeast, which is experiencing a severe drought, supplies a fair amount of area produce, said Shannon Hamn, a vegetable analyst with the U.S. Department of Agriculture. Fruits and vegetables should be able to withstand the drought in farms that are well-irrigated, she said, but if irrigation sources dry up in the coming month, "we should be looking for increased prices at the direct market level."

Perhaps the most dramatic result of the drought has been the loss of area corn. The heat has wiped out about 25 percent of the corn in both Maryland and Virginia, agriculture officials estimate. Much of the crop is grown for feed, not for table consumption. In many areas of Maryland, however, sweet corn is extremely scarce.

The lack of feed corn means less local feed for poultry growers, and chicken prices have risen in both Maryland and Virginia. A whole fryer in Maryland costs $1.05 per pound, or 21 percent more than this time last year, according to Huber. In Virginia, the increase is only a penny a pound over last year, to 77 cents a pound, according to Jan Hathcock of the Virginia Department of Labor.