An epidemic of cabin fever has broken out over the long, rainy holiday weekend but people who know say it can be cured with a little sun and a day away from other people.

From the Atlantic shore beaches to the Blue Ridge Mountains, thousands of people huddled in mountain cabins, beach houses, trailers and even tents while getting to know their families and friends a little better. A deck of cards or a portable radio were big hits in the country.

One bachelor who invited 40 people to sprawl around his big back yard was horrified when everyone tried to squeee a place in his living room.

In one mountain cabin a frustrated guest reviewed the weekend: "Charades wore out about 2 on Sunday and it was downhill from there."

Canceled barbecues left chunks of meat sitting in powerless refrigerators in some areas.

A man who drove with his wife to the Eastern Shore looked into the house, saw all the couples and the children along with a few dogs and cats and said he felt as though he was boarding an ark. "It was like war time with everyone stuck in a bomb shelter."

A father at this gathering ordered his children to go out. Their mother reminded him of the rain.

"Well send them down to the basement," he suggested.

After a short pause she said, "We don't have a basement."

Some families who stayed in the city also felt the population explosion.

"All five kids were home, in the house all day Sunday and Monday," said an exasperated parent. "They couldn't leave because of the downpour. They were bored and ate every thing in sight."

Conditions were apparently worse for 200 passengers who signed up for a "weekend cruise to nowhere" and were put ashore in Brooklyn.

About 900 passengers boarded the ship in Manhattan on Friday for a liesurely three-day cruise into the Atlantic.

"The error was in overbooking," Leonard Lansburg president of Ventura Cruise Lines and operator of the S.S. America, told newsmen shortly after the 200 passengers had disembarked and the America set out again. "Simply we goofed," Lansburg said. "Our right hand did not know what our left hand was doing."

The "Brooklyn Mutiners" complained to reporters from the wire services that overbooking was just one of several problems. They complained of long waits for dinner, vermin in the rooms, unsanitary conditions and inoperative toilets, water on stateroom floors, no water in the swimming pools, unfurnished rooms and a public address system that blared away in the night.

"It was a fiasco, the pits," said Mitebell Stein of Union, N.J. "It took six to eight hours to get our room. Then, when we saw it, there was garbage, paint cans and beer bottles all over the floor and exposed electrical wires."

Ventures has agreed to make a full refund to the 200 passengers how left the ship. Didn't cost them a cent for their trip.

Frank Dobisky of Troy, N.Y., smumed it up when he described the America as "the Love Boat gone wild."

The rain could reintroduce you to the family, a little overbooking could aquaint you with mutiny and just a little sunshine could make the holiday whole again.