Relations between Honduras and the United States have improved markedly in recent months, and a chill that began last fall appears to have ended, Honduran and U.S. officials say.

Last month, Congress approved $27 million in nonmilitary aid for Nicaraguan antigovernment guerrillas, many of whom have semi-clandestine bases inside Honduras. This funding seems to have calmed, at least temporarily, Honduras' fears that it was going to be stuck with the responsibility of the contras, as the Nicaraguan rebels are known.

Moreover, President Reagan affirmed in May U.S. readiness to help defend Honduras against possible attacks by neighboring Nicaragua, and he pledged to seek increased U.S. aid for Honduras.

Washington also quietly has accepted Honduras' shutdown of U.S. military training facilities here for Salvadoran troops, whose presence had irritated the Honduran government.

"There have been substantial advances" in relations with the United States, Honduran Foreign Minister Edgardo Paz Barnica said at a recent news conference.

A U.S. Embassy official said, "All of the concerns of the last 12 months have moved on toward being resolved. There is a sort of an upbeat feeling that things are much better than two or three months ago."

Both governments have shown a willingness to compromise. Honduras has dropped demands that the United States sign a bilateral security pact with it. The improved relations indicate that the two governments believe they share many interests, particularly their opposition to Nicaragua's left-wing Sandinista government, according to Honduran and U.S. officials.

Honduras is one of the United States' most important allies in Central America. It serves as a base for the contras and as the site of a network of U.S.-built airfields and other military installations next door to Nicaragua.

Honduras' armed forces and civilian government had welcomed increased U.S. military involvement here until the middle of last year. Relations began to cool when Congress cut off U.S. aid to the contras. Also, there was backlash here against the outspokenly pro-U.S. policies of the former armed forces chief, Gen. Gustavo Alvarez.

A barracks coup ousted Alvarez on March 31, 1984, and the armed forces' new leadership seems to favor a more nationalistic approach.

One of the principal concerns of the "new regime," as some U.S. officials call the Honduran military's new leaders, was the fate of the contras if they were permanently deprived of U.S. backing. Senior Honduran officers suggested that the Nicaraguan rebels -- who claim to number 17,000, and thus to have as many combatants as the Honduran Army -- could become an uncontrollable military force along the border with Nicaragua.

The Honduran government suggested that it might have to expel the contras from Honduras if the United States did not resume aid to the contras. But in June, the issue was defused for the time being when Congress reversed itself and agreed to provide nonmilitary aid to the rebels.

"The Honduran government wanted a definition of U.S. policy toward the contras," a Honduran government official said. "Now we have it."

In another turning point for U.S.-Honduran relations, President Reagan pledged May 21 that the United States would, if necessary, help Honduras "to defend its sovereignty and territorial integrity against communist aggression."

This public commitment, made during a visit to Washington by Honduran President Roberto Suazo, fell far short of the Hondurans' repeated demands for a security treaty with the United States. But the Hondurans "appear to be satisfied for now" with Reagan's statement, a U.S. official said.