Supermarket prices in the Washington area soared by 2.6 percent in June over the previous month, rising nearly twice as rapidly as they normally do in June, the Labor Department reported yesterday.

The price increases that confronted customers at Washington area grocery stores last month were significantly steeper than in June of last year, when food prices climbed by 1.8 percent. In June 1976, the increase here was 1.6 percent.

"Every week it's a different price," Wilma Jones complained yesterday as she stopped at a Safeway store on Columbia Road NW. "Prices go up every week. One week it's three for 89(cents); the next week it'll be two for 89."

To try to beat the rising prices, she is buying more liver and hamburger. "But," Jones said, " my children say, 'Momma, all you buy is liver and hamburger.' But there ain't nothing we can do. people gotta eat."

"It's terrible. It's much worse. Every month it's worse," complained another woman who was shopping at a Giant Food store on Columbia Road.With five children to feed, she said, "Lots of things you need you have to leave off."

The biggest price increases here last month were for meat, poultry and fish, which rose in cost by 5.4 tics. Beef prices climbed especially steeply, the Labor Department said.

Dairy prices rose by 2.9 percent in June. These had decreased in May. Cereal and bakery prices increased by 2.2 percent last month. Prices declined in June for a few products - eggs, tomatoes and bananas, the department said.

A comparison of ads that appeared in The Washington Post yesterday and in January showed a 53 percent price increase for round beef, from 78 cents a pound to $1.19 a pound now. Potatoes also showed a sharp increase, from 99 cents for a 10-pound bag in January to $1.39 for 10 pounds yesterday.

According to the advertised prices, some food products such as eggs and corn have risen in price since January.

Others have increased only slightly. Milk prices have climbed to $1.39 a gallon from $1.29 in January, and English muffins showed and increase during the six months from 65 cents for 12 to 75 cents for 12.

Supermarket prices rose more sharply in the Washington area last month over the previous month than they did in the United States as a whole. Nationally, food prices increased by 2 percent, on an unadjusted basis. Food price rises reported by the Labor Department for the Washington area are not seasonally adjusted.

The surge in supermarket prices here last month also exceeded the 1.7 percent increase that occured in May. Grocery prices here have risen by 11.6 percent since December, according to the Labor Department. The average monthly increase has been 1.75 per cent during the past six months.

According to Giant spokesman Barry Scher, weather was a major factor in recent increases in food prices here. Excessive reainfall in California hurt fruits and vegetable crops, he said. He added that Giant also has faced increasing operating expenses, including utility costs. Scher forecast a slowdown in price rises here during the remainder of the year.

To help keep grocery bills down, consumer affairs advisers for both Giant and Safeway - the Washington area's major food chains - urged consumers yesterday to rely on what have become standard techniques. These include examining unit prices, buying house brands, using coupons and carefully preparing a shopping list. Safeway recently began a promotional campaign to alert its customer to sales to help fight inflation.

For Ernest Brown, who was shopping at a Giant supermarket yesterday, the outlook, nevertheless, appears grim. "The year is 1978. Ain't nothing going down," he said. "You either budget your money or starve to death."