Cherry Blossom Peak Bloom: The science behind predicting one of DC's biggest spring traditions

WASHINGTON - It’s a spring rite of passage in the District: a photo beneath a fluffy, pink and white blossoming cherry tree. 

There are 3,750 cherry trees that surround the DC tidal basin. Each year thousands of tourists and Washington residents alike flock to the area in hopes of catching the trees at peak bloom, defined by the National Park Service as when 70 percent of Yoshino cherry trees are fully blossomed. 

While the blossoms seem to come out like clockwork, there is a science behind knowing when the trees will bloom. For the National Parks Service, horticulturist and turfgrass specialist Michael Stachowicz is that master bloom forecaster. 

“I take it very seriously,” Stachowicz said. 

During the year, Stachowicz helps keep the National Mall’s grass green. But, once a year, he is the go-to guy when it comes to one of DC’s most iconic sights 

“It’s nerve-racking,” Stachowicz described. “If you can tell me what the weather's going to be, I can tell you what the bloom is going to be within reason, within a few days.”

Stachowicz said he looks at a number of things, including historical data. But it really comes down to the temperature and the weather conditions as Washington transitions into spring, which can often be unpredictable. It’s a fact that DC residents like Lauren Jobe understand. 

“You just never know what weather will be, it could be 80, it could be 30 degrees,” Jobe said. “They're definitely worth the hype. They’re gorgeous.”

For the last four years, Stachowicz has been predicting the pink petal's timing. The tracking begins back in the fall when the cherry trees go dormant. 

Stachowicz said some years are easier than others, but this year has been particularly tough. In February, the peak bloom was predicted for mid-March because the data seemed to suggest an early warm-up. But back-to-back nor’easters and snowstorms pushed the big day back to the second week of April. 

“There are some processes out there that we can predict, this is one we can kind of predict,” Stachowicz said. 

Ultimately, the peak bloom period began on April 5, a few days ahead of schedule.

And there’s a lot riding on Stachowicz’s prediction. Not only does the National Cherry Blossom Festival plan around his prediction, people around the world count on his accuracy in hopes of seeing the nation’s capital awash in pink.

Even with all the modern tools and techniques, Stachowicz reminds folks he is dealing with mother nature and sometimes she changes her mind.

“I don't want this prediction to be something mystical,” Stachowicz said.