Washington’s centennial cherry blossom bloom will probably take place early this year and happen from March 22 through early April, a government expert announced Thursday.

Robert DeFeo, the National Park Service’s veteran blossom forecaster, said the peak bloom was likely to occur between March 24 and March 31.

His pronouncement came at the annual unofficial kickoff of the annual National Cherry Blossom Festival, which this year marks 100 years since the cherry trees were first planted on the Tidal Basin on March 27, 1912.

Technically, the Blossom Festival’s birthday bash — expanded from about two weeks to almost six this year — doesn’t start until March 20 and runs until April 27. But some events are starting already. National Geographic’s exhibit on the samurai and the photographs of Japan lover Eliza R. Scidmore opens next week. So does a display of exotic embroidery at the Japan Information and Culture Center.

Also starting early has been the warm weather — which can accelerate the bloom. In February, the temperature went below freezing on only four days, and it reached 50 or above on at least 16 days. It zoomed to 72 on Feb. 1.

But DeFeo, the National Park Service’s veteran cherry blossom prognosticator, said Tuesday that the earlier weather is moot.

“It really only matters as to what happens from now on,” he said. “All the warm weather before did not move the cherries along. But now, yes. Now is the time where, if it gets really, really warm, things could accelerate.”

According to the Capital Weather Gang, temperatures over the next week or so could be generally above normal, and DeFeo said, “My gut tells me [the bloom] might be a little early.”

“If it got up in the 60s and 70s and stayed there for 14 days, we’d have the things be in bloom,” he said.

But take heart, he said Wednesday: “They’re not leaping; they’re creeping.”

An early start could mean an early end and could leave the closing weeks of the extended blossom festival with no cherry blossoms. The blooming period is usually about two weeks, more or less.

The average peak bloom date is April 4, but the capricious blossoms have peaked as early as March 15, in 1990, and as late as April 18, in 1958, according to DeFeo’s records.

Although it seems highly unlikely, a March 15 date this year would put the bloom at its peak before the festival even starts and leave most of the celebration blossomless.

Last spring’s blooming ran from March 26 through April 4, according to the National Park Service.

Unease over the potential for an early bloom has reached some of the highest levels.

The Japanese ambassador, Ichiro Fujisaki, who thinks the cherry blossoms and the Statue of Liberty are the two greatest gifts to the United States from abroad, recently expressed concern about the temperatures.

“My only worry [is] weather,” he said in an interview. “Too warm. My concern is everything’s going to be finished before March 20th. How can we celebrate when all the leaves are there?”

The festival is marking the centennial of the first planting of Japanese cherry trees on the Tidal Basin on March 27, 1912, by first lady Helen Taft. The initial 3,020 trees were a gift of friendship from Tokyo to Washington.

Within a decade, tens of thousands of visitors were flocking to the Tidal Basin to see the trees. And since then, the blossoms have become one of the city’s premier tourist attractions and an international hallmark of Washington.

This year, first lady Michelle Obama is serving as honorary chairman of the festival, which will be augmented by the new Martin Luther King Jr. Memorial in the middle of the Tidal Basin blossom belt.

The annual blossom parade is set for April 14, and the Smithsonian Institution, the Library of Congress and the National Gallery of Art have scheduled special exhibits marking the centennial.

The forecast for Thursday was for sunny weather, with a high of 66. Somewhat cooler temperatures are predicted for the weekend and early next week.

“Every night before going to sleep,” Fujisaki said, “I pray: ‘Fall the snow. Blow the cold wind.’ ”