WASHINGTON -- Washington's famous cherry blossom trees reached peak bloom Thursday, just in time to provide a colorful finale to the city's spring festival, the National Park Service said.

Park officials had predicted the peak bloom would arrive between April 8 and April 12, and they bloomed on target. Peak bloom means at least 70 per cent of the trees around the Tidal Basin are blossoming with pink and white flowers.

The Yoshino cherry trees usually bloom for seven to 10 days, said park spokesman Brian Hall. The length of the blooming period depends on the weather. Strong winds and rain can blow the petals off all the flowers within minutes, but the forecast looks good.

"We're going to have a great weekend," Hall said. "It's supposed to be great weather, so we're expecting good crowds."

Park officials encourage visitors to use mass transit or to park away from the Tidal Basin area to avoid traffic jams.

The National Cherry Blossom Festival runs through Sunday. It includes a parade and a Japanese street festival on Saturday. Buildings around the nation's capital have been lit in pink for the festival. This year marks the 102nd anniversary of the gift of the cherry blossom trees from Japan as a symbol of friendship.

This year's peak bloom comes slightly later than average due to cold weather in March. The average bloom date since 1992 is March 31. Last year they reached peak bloom on April 9. The trees bloomed as late as April 18 in 1958.