As winter's first snow turns to slush, Northern Virginia's two members of the House of Representatives are heading for sunny Spain, on separate congressional junkets.

Rep. Herbert E. Harris II of Fairfax County is scheduled to leave Andrews Air Force Base this afternoon for an 11-day visit to Spain and a stop in equally sunny Portugal on the way back.

Rep. Joseph L. Fisher of Arlington will spend most of his week-long trip is not-so-sunny Eastern Europe, stopping in Madrid for a day on the return trip.

The two liberal Democrats are continuing a time-honored tradition -- carried to the zenith by former Virginia senator William L. Scott -- of taking taxpayer-financed trips during congressional recesses.

Scott's successor, Republican Sen. John W. Warner, avoided taking congressional trips in his first year. That was in marked contrast to Scott, who visited 38 countries in his single six-year term in the Senate. Warner also was one of only four members of the Senate who didn't miss a roll call vote in 1979, according to his staff.

Warner will slip out of town next week with his wife, actress Elizabeth Taylor, for a private vacation at his own expense. The state's senior senator, Independent Harry F. Byrd Jr., also vacationing privately, in the Caribbean.

Both Fisher and Harris will be accompanied by their wives, who fly free on military planes. Both congressmen said they will reimburse the Congress for their wives' personal expenses, although that is not required by law.

Other area members of Congress will stay closer to home, Rep. Gladys Noon Spellman (D-Md.) has planned to conduct field hearings in Hawaii, Alaska and California, but cancelled them at the last minute.

Rep. Beverly B. Byron (D-Md.) will visit defense contractors on the West Coast. An aide said she will be briefed on the M-X and Cruise missiles at Boeing in Seattle and General Dynamics in San Diego, Byron, who is a member of the House Armed Services Committee, will travel on commercial airlines but send the bill to the government.

Sen. Charles McC. Mathias (R-Md.), the only area member of the Senate facing reelection this year, is traveling throughout Maryland in a warmup for the campaign.

Harris will leave Andrews Air Force Base this afternoon on a trip arranged by Rep. John Brademas (D-Ind.), the deputy majority leader of the House. Also in the delegation will be Reps. Harold C. Hollenbeck (R-N.J.), Tom Railsback (R-Ill.), Charles B. Rangel (D-N.Y.), Benjamin S. Rosenthal (D-N.Y.), and four staff members.

An aide to Harris said the Virginia Democrat "doesn't know how he got picked."

The Brademas group will visit Barcelona, Seville, Toledo and Madrid, Spain, and Lisbon, Portugal. They will meet with local political leaders and inspect a U.S. naval base at Rota and a U.S. air base at Torrejon.

The delegation will return Sunday, Jan. 20, they day before the start of the second sesson of the 96th Congress.

Fisher will be traveling as a member of the trade subcommittee of the House Ways and Means Committee, in a trip organized by subcommittee chairman Charles Vanik (D-Ohio).

Eight members of the House, plus seven wives and five staffers, will make up the delegation, which will discuss trade and immigration issues in five cities.

The Vanik party will leave Andrews Thursday morning and after a refueling stop in Torrejon, Spain, will make one-day visits to Geneva, Switzerland; Bucharest, Romania; Budapest, Hungary; Sofia, Bulgaria, and Madrid, returning to Andrews on Jan. 16.