Gasoline prices, which traditionally rise during the summer, are falling instead and may drop as much as 10 cents a gallon by late winter, government analysts said yesterday.

Retail gasoline prices have dropped almost 1 cent a gallon since the beginning of the summer and are expected to fall from an average of $1.22 a gallon in June to $1.13 by the first quarter of 1986, according to the Energy Information Administration, a statistical and analytical arm of the Energy Department.

Other oil industry specialists say the decline may not be that steep and caution that prices probably will not fall as much in the Washington area, where gas traditionally costs at least 5 or 6 cents more than the national average.

In the Washington area, an informal survey of 20 service stations by The Washington Post found that prices for regular leaded gasoline ranged from $1.089 a gallon at stations in Wheaton and Silver Spring (self-service and cash) to $1.569 a gallon at an Alexandria station (full-service and cash or credit).

Prices for regular unleaded ranged from a low of $1.169 (self-service and cash) at stations in Wheaton, Franconia and Silver Spring to a high of a $1.619 (full-service and cash or credit) at stations in Gaithersburg and the District. Prices for unleaded premium ranged from a low of $1.279 (self-service and either cash or credit) at stations in Franconia and in the District to a high of $1.699 (full-service and credit) at another D.C. station.

Residential heating-oil prices also are expected to fall, the government agency said. Normally, residential heating-oil prices could be expected to begin rising this month as heating-oil companies begin building supplies for the winter, but the EIA says consumers this fall can expect to pay about $1.02 a gallon, about 3 cents per gallon less than they paid a year ago for home heating oil.

In addition to decreased gas and heating-oil prices, consumers also may benefit from lower prices for natural gas this winter as a result of growing competition among pipeline companies and natural gas producers, industry officials and analysts say.

Experts said that industrywide deregulation and a sharp decline in the demand for natural gas have created a buyer's market that may cause the price of gas for the homeowner to drop by at least 5 percent.

The continuing decline in gasoline prices is expected despite an anticipated increase of about 2 cents per gallon in production costs. The increased costs are expected to result from government orders to reduce the lead content of gasoline.

Under a directive from the Environmental Protection Agency, the first step in the gradual reduction of lead content took effect July 1, when the standard was dropped from 1.1 grams of lead per gallon to 0.5 gram. The next phase begins Jan. 1, when lead content must be reduced to 0.1 gram.

"It takes more crude oil to make unleaded gasoline, and it takes more expensive octane enhancers to replace lead, which is the cheapest octane enhancer," said Dan Lundberg, an oil industry analyst who publishes a weekly survey of gasoline prices.

The average price for gasoline during the third quarter of the year, which ends Sept. 30, is expected to drop to $1.21 per gallon, down 1 cent from the second quarter, the EIA said in its "Short-Term Energy Outlook -- Quarterly Projections."

"The projected decrease between the second and third quarters is in contrast to the usual price rises at this time of year due to heavy summer driving," the agency said. "The EIA projects its decrease this year because of falling crude oil prices and because second-quarter gasoline prices were unusually high."

"We had a meteoric rise from the very depressed level of gas prices earlier this year," said Sanford Margoshes, an oil industry analyst with Shearson Lehman Brothers. Margoshes said he doubts that prices will fall by as much as 10 cents. Lundberg said that the national average price of gas has dropped over the past two weeks by just over a half-cent a gallon.

"This is due mainly to the continuing erosion of wholesale prices, which dropped almost a penny a gallon over the same period," Lundberg said.

The average overall price nationwide for all grades of gasoline is $1.234 per gallon, Lundberg said. Two weeks ago, the average overall price was $1.239 per gallon. The nationwide average for regular leaded gas was $1.12 a gallon at self-serve pumps. Regular unleaded gas currently averages $1.19 per gallon, Lundberg said.

The Organization of Petroleum Exporting Countries' price for crude oil fell more than $2 a barrel this year. A glut is expected because Saudi Arabia announced an increase in crude-oil production from 2.2 million barrels a day to 3.5 million, Lundberg said. "This inevitably will bring reduced crude oil prices to move the increased production," he added.

The EIA said that gasoline prices would average $1.15 a gallon in 1986, compared with $1.19 a gallon forecast for this year and $1.20 a gallon paid in 1984.