Washington’s famed cherry blossoms will probably hit peak bloom between March 26 and March 30 this year, signaling the unofficial start of spring.

National Park Service officials announced the peak bloom dates Monday at a news conference to preview the annual National Cherry Blossom Festival, commemorating the anniversary of Japan’s gift of 3,000 trees to Washington in 1912. This year’s festival runs March 20 to April 14.

The peak bloom date is the day on which 70 percent of the blossoms are open. The average peak bloom date is April 4; last year’s peak date was March 20.

The first festival was held in 1927. Today, more than 1.5 million people visit Washington each year to see the trees surrounding the Tidal Basin.

At Monday’s news conference, Mayor Vincent C. Gray (D) called the festival an integral part of spring.

“D.C. is a springtime destination for not only the city, but for the nation and the world,” said Gray, who wore a pink tie. “The Cherry Blossom Festival is a central piece of that.”

Traditionally, first ladies have been involved in the festival. On March 27, 1912, first lady Helen Taft and the wife of the Japanese ambassador planted the first two trees in West Potomac Park.

First lady Michelle Obama was the honorary chair for last year’s centennial festival and followed in Taft’s footsteps by planting a cherry tree in West Potomac Park. This year, 150 additional trees will be planted there.

The three-week-long festival features activities to celebrate the blossoms and Japanese culture, including a Japanese street festival, bike tours and art and fitness components.

A free festival app will be available to plan activities in advance and follow festival updates in real time.

Ambassador John Malott, the president and chief executive of the Japan-America Society of Washington D.C., stressed the importance of the festival in preserving ties between Japan and the U.S.

“We continue to lay the foundation for another century of friendship between the United States and Japan,” he said.