"That's the first," said Mary Krug of the National Park Service, pointing to a delicate light pink bloom on a Japanese cherry tree near the southern shore of the Tidal Basin.

"The tree has been out two days already," she said. "It's amazing how much they change from day to day - everything is coming to life, even the people around here."

The little cherry tree that blossomed earlier than the thers - along with magnolia blooms seen elsewhere in the city - surprised even the park service's horticulturist who went to the Tidal Basin yesterday to predict when the rest of Washington's 2,100 cherry trees will blossoms this year.

"The cherry blossoms are five to seven days away from bloom." Harold Green, the horticulturist, pronounced as he gently held a branch of budding cherry blossoms between his fingers.

"After that, they will take another five days to reach their peak, and they will stay in full bloom for about five days," he forecast.

If Green is correct, the cherry trees should be in the prime of their splendor for the annual National cherry Blossom Festival, scheduled this year for March 28 through April 2.

It also will be only the second time since 1970 that the blossoms and the festival will have happened at the same time.

Green warned that the caprices of Washington weather could injure the blossoms or prevent them from making it to the festival at all if temperature slan to the 30s.

"If it gets close to the 20s, we'll have problems," he said, explaining that a hard freeze could kill the buds before they bloom. A light frost in the high 30s, on the other hand, "would just burn them," leaving a brown tinge on the edge of the blossoms, he said.

As he watched the branches of the cherry trees sway in yesterday's stiff breeze. Green warned that high winds or heavy rains also could damage the fragile blossoms.

The National Weather Service said yesterday its long-range forecast for the rest of March does not include any temperatures below freezing.

"Right now, we don't see any low temperatures coming this way," said a weather service spokesman. "But that's always risky. This area always seems to get a frost in late March."

Throughout the area yesterday, trees were coming to life, bringing hints of color to the drab winter cityscape under unseasonably warm skies.

At Scott Circle, near the scene of one of last week's terrorist sieges, cherry trees were budding. Along the city's avenues, summer shade trees including maples, elms and oaks were beginning to show their first tentative colors.

Green, the park service horticulturist, said the extreemely cold weather in January and February did not affect the city's most colorful trees, the Japanese cherry trees.

"The hollies, azaleas, camellias, rhodondendrons, the trees and shurbs that don't drop their leaves like broadleafed evergreens, are the ones that were hurt by the cold," Green said.

He explained that the cold weather froze the ground and dried out the leaves on those trees and shrubs. The leaves were unable to replenish their moisture because roots could not get water from the frozen ground.

"Washington is a transitional area," Green said. "It is the northern limit for some southern plants and the southern limit for some northern plants. We have a variety of plants here that don't grow anywhere else. "Severe hot or cold weather hurts."

Gordon Cheridan, manager of the house plant section of Johnson's Flower Center, 4020 Wisconsin Ave., NW, said the severe cold weather also affectedindoor plants.

"The biggest problem with indoor plants was dryness," Sheridan said. "People turned up their heat but stayed on whatever schedule they had for watering their plants.

"You have to water the plants more often when you have dry, heated air in the house," he explained.

Helmut Jaehnigen, a nurseryman for 17 years at the Behnke Nurseries Co., in Beltsville, said rubber trees, evergreen shrubs and hollies may have been browned around the edges because of the cold weather.

"You'll have to cut back the bush until you find green, juicy wood," Jaehnigen said. "That's where they'll bloom out.

In the city, the District of Columbia government has begun planting new trees since the cold weather has passed. Usually the trees are planted throughout the winter but this year's cold prohibited that.

Martin Bell, a horticulturist for the tree and landscaping division of the Department of Transportation said the city now is planting 6,000 trees.

Bell said every tree in the city is registered in a computer that retains the tree's history and indicates when the tree needs to be replaced.

He said the city's oaks, maples, elms and other shade trees will not be hurt if a sudden frost hits the area.

This year's National Cherry Blossom Festival, which marks the unofficial beginning of the Washington tourist season because of the popularity of the blossoms, will begin as usual with the lighting of a 300-year-old Japanese lantern at the Tidal Basin.

The lantern will be lit by Mayor Walter E. Washington and the Japanese ambassador while a visiting girl's choir from Japan performs.

As usual, the festival will include a luncheon fashion show and the presentation of festival princesses from each state during he grand parade on Constitution Avenue NW. on April 2. The festival will end that night with a ball, where a festival queen will be chosen from the princesses by the spin of a wheel of fortune.

Tickets for seating at the parade areon sale at Ticketron, Pentagon Ticket Service and the Jaycees office, according to Louise Kelly, chairwoman of the parade.