President Reagan, showing interest at an unusually early point in Virginia's gubernatorial campaign, will travel to the state this month to help raise money for Republican Wyatt B. Durrette, according to state party and campaign officials.

The move by Durrette and GOP officials to involve Reagan this early indicates the intensity of the race against Democratic nominee Gerald L. Baliles and suggests a more active summer than normal in Virginia politics, officials in both parties said.

"For some reason people are focusing on this race, the top of the ticket, earlier than is traditional," said Don Harrison, Durrette's press secretary. Harrison said the two candidates are "breathing neck and neck" with fewer undecided than the normal one-third of the voters, a view generally shared by Baliles' campaign.

Reagan is scheduled to appear in Richmond July 30 for a Durrette fund-raiser after visiting a national Boy Scouts gathering at Fort A.P. Hill, according to campaign officials. The White House, following standard policy, declined to comment in advance on the president's travels.

Reagan was last in Virginia in May for an appearance at Colonial Williamsburg to promote his tax revision plan.

Asked about the purpose of any Reagan trip, Harrison replied "finances." But Durrette's campaign dismissed suggestions that the early visit indicated fund-raising problems or concern about Baliles. The campaign said it expects Reagan to make another visit this fall.

In his latest campaign finance report last week, Durrette, a Richmond lawyer, showed contributions of $1.2 million, with $200,000 on hand and about $75,000 in debts. Baliles reported today that he had $1.7 million in contributions, about $230,00 in debts and $117,000 on hand.

Baliles' campaign said it had raised $330,000 in the last 30 days and had paid off about $150,000 in debts from Lt. Gov. Richard J. Davis' campaign for governor against Baliles -- a debt Baliles agreed to help retire when Davis withdrew from the race.

Both Durrette and Baliles have said their general election campaigns may cost as much as $3 million each.

"The president of the United States is always welcome in Virginia," Baliles said today in response to the announcement.

Reagan's campaign appearances in the state have produced mixed results in the past.

In 1982, Reagan supported then- Rep. Paul S. Trible in his successful race for the U.S. Senate against Davis.

However, in 1981, a year after Reagan's first presidential election, visits by Reagan, First Lady Nancy Reagan and other top national Republicans failed to put then-attorney general J. Marshall Coleman in the governor's office.

Coleman lost to Democrat Charles S. Robb, who under Virginia law cannot succeed himself.

Coleman was criticized for attempting to make the 1981 campaign a "referendum on Reagan," a move Durrette so far has avoided this year. In addition to appearances by the Reagans for Coleman, the president also taped a two-minute commercial for Coleman in 1981 and met with him for 20 minutes at the White House.

"I think it's helpful; it gives rise to an aura of good feeling," Coleman said today, saying Reagan is "the person with the single most credibility in America" as a politician. Reagan easily won Virginia in 1980 and last year.

Sandy Scholte, political director for the state Republican Party, said today that the presidential visit can be expensive for the sponsoring campaign and party.

"All political time will be billed, including communications. It's not just dropping by," Scholte said of Reagan's entourage. Scholte said the Reagan visit in 1982 for Trible cost about $50,000, but said the party and candidates stand to gain more than they pay out in publicity and donations.

Virginia and New Jersey are the only states with races for governor this year. Republican Gov. Thomas Kean is considered a heavy favorite for reelection in New Jersey, so both national parties are expected to focus their resources and time on the Virginia race.