Neither rain nor sleet nor heavy traffic nor crowded stores could keep Robustiani Barrera and his family away from the Neiman-Marcus stores on Wisconsin Avenue yesterday. After all, Christmas was only 30 days away, and there were gifts to be brought.

Barrera, a physician from Cumberland, Md., said his family planned their trip to Washington a week ago and were disappointed to see the rain yesterday. But they came anyway.

"It's first time in the stome." Barrera said, as his 7-year-old son and 21-month-old daughter squeled delightedly at the antics of the windup toy dog they were playing with on the store's second floor. "It's beautiful."

Thousands of Washington area residents, and their own-of-town relatives and friends who had come for Thanksgiving, began their Christmas shopping yesterday.

And many of those who weren't Christmas shopping aparently spent the day at the Smith-onion's Air and Space Museum.

About 60,000 men, women, and children - browsed through the museum yesterday between 10 a.m. and 5:30 p.m. - so many people that twice during the day, guards had to shut the doors briefly so that no more people could enter, according to a more people could enter, according to a spokeswoman for the museum.

"I think everybody must have spent the day right down here," the spokeswoman said. She said that about 8,000 people can fit into the building, which she called the "world's most popular museum," at one time.

Yesterday's crowd didn't set a record, however. That occured last July, when 87,000 people visited the museum in one day, the spokeswoman said. She added that huge crowds during the day after Thanksgiving last year also forced the guards to shut the doors to keep people out temporarily.

A spokesman for the Museum of Natural History reported that crowds were "quite heavy" there also yesterday, though no specific figures were available.

At the Anacostia Neighborhood Museum, located at 2465 Martin Luther King Ave. SE, the only children's tour group scheduled for the day called in to cancel, leaving the museum's displays on the "Anacostia Story" and "Anacostia Blacks in the Military" relatively unseen.

The group that canceled was a private day care center. "Many parents are at home and decided to keep their children home, too," explained Zora Martin Felton, director of education at the museum. That fact, plus the rain, combined to keep attendance down, she said.

Yesterday's weather began dismally and didn't improve. A National Weather Service spokesman said that sleet was reported yesterday in areas north and west of the Washington metropolitan area, including Hagerstown and Frederick. Sleet also was reported in Bethesda around mid-morning yesterday, the spokesman said.

The temperature reached a high of about 44 degrees in the area yesterday, the spokesman said. A few lingering snow flurries are expected this morning to begin a windy and cold day, he added.