Visitors are flocking to Washington's annual cherry blossom festival to marvel trees donated by Japan more than 100 years ago.

The US capital has more than 3,000 cherry trees, including the Somei Yoshino variety and others provided by the mayor of Tokyo in 1912.

The festival heralds the blooming of the flowers. This year, the event began on Monday.

The National Park Service expects peak bloom to arrive a week to 10 days earlier than usual, due to a warmer winter.

A Washington resident who said he enjoys the flowers every year said he feels happy and proud of the fact that the trees were given by Japan and symbolize friendship.

More than 1.5 million people are expected to visit the festival through April 16. Events showcasing Japanese culture and food are planned during the period.