Pinpointing ‘sakura’ arrival serious business, fine science


When spring comes, millions of Japanese happily turn their thoughts to one thing: When will the cherry blossoms start blooming?

“Sakura” cherry blossoms, a symbol of Japan, last only about a week, so arranging a sakura-viewing party with friends or family at just the right time is a matter of keen concern for many in pursuit of this particular seasonal joy.

Though generally off by only a few days, the Meteorological Agency has often been criticized for inaccurately predicting the arrival of the cherry blossoms.

But now the agency has some competition: the Japan Weather Association and Weathernews Inc.

The pair are trying to crack into the market by giving sakura lovers more accurate and detailed predictions.

“It’s better that we have three predicting organizations now,” said Hirofumi Nakayama, a worker at Hamamatsu Flower Park in Shizuoka Prefecture.

Hamamatsu Flower Park boasts 1,100 sakura trees, including 500 of the popular “someiyoshino” variety, and sets up illuminations for night viewing.

But last year, the Meteorological Agency got its prediction badly wrong after inputting the wrong data into its supercomputer.

The agency forecast sakura would start blooming on March 13, 15 days earlier than usual, but the trees started budding on March 21 in Shizuoka.

Timing sakura is serious business for various sakura-related industries.

Tourism agencies arrange tours to famous viewing spots. Parks and city governments organize sakura festivals and stores must stock up on “bento” boxed meals for sakura parties at the right time. Companies also reserve sites and times for viewing parties.

“We started making predictions because so many people every year ask when sakura will start blooming,” explained Chie Tanaka, spokeswoman for Japan Weather Association, which started challenging the Meteorological Agency two years ago with its own sakura predictions. Japan Weather Association, established in 1950, is a nonprofit foundation affiliated with the transport ministry.

Tanaka said the foundation is making predictions for 87 locations across the country this year, including many cities and towns the agency has stopped covering as part of the government’s budget-cutting efforts.

The Meteorological Agency made predictions for 107 locations in 1996, but that number has dropped to 68 this year as local meteorological stations continue to close.

Following a personnel-cutting goal finalized in 2006 by then Prime Minister Junichiro Koizumi, the agency now plans to further reduce the sakura-prediction sites to 53 in 2011.

Meanwhile, Weathernews Inc., a private weather service, has adopted an approach totally different from its two rivals: It asks tens of thousands of volunteers to send in photos of sakura buds by e-mail.

Predictions by the Meteorological Agency and Japan Weather Association are largely based on the analysis of past blooming times and temperature patterns in January, February and March.

Weathernews supplements this approach with images sent in by registered volunteers, who also pinpoint the location, the estimated age of the tree and the sunshine conditions.

The predicted date is then uploaded on the firm’s Web site.

More than 10,000 volunteers across the country took part in the Sakura Project in its inaugural year last spring, according to Weathernews.

This year, there were 17,831 registered participants as of Friday, and the number is expected to increase as the blooming season approaches, said Yuka Yoda, spokeswoman for Weathernews.

“Japanese are very, very interested in when sakura will start blooming,” Yoda said.

“Every participant is enjoying watching the sakura every day” and sharing the information with others, she said.

For the latest predictions, visit the Meteorological Agency site at or Japan Weather Association’s site at or the Weathernews Web site for the Sakura Project at