Pearl Kollar, a retired machine operator from Shelby, Ohio, sat on a concrete wall outside the White House yesterday, nursing tired feet and wiping perspiration from her forehead.

Looking at the White House line that stretched up the block, she guessed it would be another hour and a half before she would get in.

Nevertheless, Kollar, who wore pink-rimmed sunglasses and tennis shoes, said she was having a good time here. "But, what I am going to enjoy the most is when I'm back home, and there will be a picture on TV of the Rotunda or the White House, and I'll think, 'Hey, I saw that. I've been there.' "

One of Washingtonians' favorite pastimes seems to be bad-mouthing tourists for the traffic headaches and long lines they create, but Kollar and other visitors yesterday had mostly good things to say about the nation's capital.

"I don't feel weird being a tourist," said Kollar. "No, because this is mine. This is yours. It's everybody's. It's all ours, every bit of it."

Orbie Case, 41, and Henry Kidd, 39, rested in the sun outside the National Museum of American History. It was their first trip to Washington, and they had come as chaperones with the New London, Ohio, high school band.

"Heck no, we don't feel weird being tourists," Case said. "You're the only one we've met so far who's from Washington."

They had been here since Saturday and, so far, they were most impressed by the Hope diamond and by the city's abundance of tulips, azaleas and trees.

"You're about six weeks ahead of Ohio, with the leaves and everything," said Case. "We can't believe the trees. At home, everything's just starting up. Before, all I knew about Washington was what they have on the TV and from the post cards, but this is really fantastic."

Many of the tourists left locations where it was still spring to arrive in a city that was experiencing a taste of summer. The temperature at National Airport yesterday reached 88 degrees, just 1 degree short of the record for the date, set in 1976. Today's high is expected to be in the mid-80s.

Holly Craker, 35, and Mary Bedell, 47, of Springfield, Mo., came to Washington to join the thousands who demonstrated this weekend against President Reagan's policies on Central America, South Africa and other issues.

Yesterday about 1 p.m., they walked the hot sidewalks outside the Treasury Department building, wearing visors that said "Washington."

Both said they found Washington's radiating street pattern confusing. "I don't know what they can do about it," said Bedell. "It's already laid out like this."

But what disturbed the women most were Washington's street people.

"Something should be done about the homeless in this town," said Craker. "It's real depressing to come to your nation's capital, where you're supposed to have some pride, and see all these people who are wandering around with nothing to eat."

Sitting in the grass at the Ellipse, near a hot pretzel and eggroll truck, was Philip LaBar, 45, an oil burner technician from East Stroudsburg, Pa., and his wife Martha, 42, a United Way caseworker.

"I'm amazed at how clean Washington is, considering the number of people I see," said Martha LaBar.

Also in town yesterday were 113 seventh graders from the Shaler Junior High School in Pittsburgh. They wanted to see the White House, and they desperately hoped to catch a glimpse of Reagan.

As for Washington, the city?

"I like it," one called out.

"Too crowded," said another.

"Strange people."

"How about that guy wearing the skirt? That was the craziest," said a fourth.

Preferring the sun to the sights were three students from Long Island's Floral Park Memorial High School, relaxing on benches at the Mall in black punk sunglasses, waiting for the bus home.

"We're going to go back with tans, and they're going to be all white up there," said Eusebio Teixeira, 17, who was sunning his chest.

The three had found souvenir cutoff T-shirts, which they said would be perfect in New York's summer heat. Erik Rittsteuer, 18, had bought a coffee mug for his mother. He pulled it out of a paper bag. It said "No. 1 Mom -- Washington, D.C."