The magnificent cherry blossoms at DC's Tidal Basin draw more than 1.6 million visitors every spring, but timing a trip to see them at their primate be an adventure. That's because the peak bloom date is heavily influenced by weather, and can swing by weeks depending on how late winter and early spring behave.
Most years, peak bloom lands between the last week of March and first week of April, but in some years it can be considerably earlier or later.
The National Park Service defines peak bloom as the day when 70 percent of the Yoshino cherry blossoms are open around the Tidal Basin.
The 6 stages of the bloom cycle
The Park Service tracks the Yoshino buds through six stages, from the first green tip to full flowering:
- Green buds
The first visible sign that dormancy is ending: small green buds appear. - Florets visible
Individual flower structures become visible within the bud. - Extension of florets
The florets lengthen as the bud swells. - Peduncle elongation
The small stems supporting the blossoms lengthen. - Puffy white (of puffy blossoms)
Buds look swollen, as if they’re about to pop. - Peak bloom
70 percent of Yoshino blossoms open.
Early stages progress at a snail's pace during cold spells, but the buds can fly through the final stages during warm stretches.
How weather controls the blossoms
Bud development begins during the first sunny and mild days in late February and early March. Sustained mild weather accelerates bud development, and promotes early peak blooms.
Cool stretches slow development. And a late freeze can damage blossoms, reducing bloom quality. The buds become vulnerable to freeze damage once they reach fourth and fifth stages and their flowers become exposed. Usually, the temperature needs to drop into the 20s for several hours for bud damage to occur.
In mid-March 2017, snow and freezing weather followed an unusually warm start to the month and many buds, already at Stage 4 and 5, were damaged.
How long peak bloom may last
Once peak bloom occurs, the question becomes: How long will peak last? In calm, chilly weather blossoms can hang around for a week to 10 days; the chilly weather acts like a refrigerator, preserving the flowers. But soaking rain, and strong winds can strip petals and unusually warm weather can cause them to wilt.
Peak bloom timing: average, earliest, latest
The Park Service notes peak bloom is most likely between the last week of March and first week of April.
- Earliest peak bloom on record: March 15 (1990)
- Latest peak bloom on record: April 18 (1958)
The long-term average peak bloom date – from 1921 to present – is April 4, while the more recent average, over the last 30 years, is around March 30.
Has climate change shifted peak bloom?
Yes — the signal has become hard to miss.
As March temperatures have risen over the past century, the average peak bloom date has moved earlier by about a week. Peak bloom has occurred earlier than the normal for the past seven years.
This does not mean every year is earlier than “normal.” Weather still swings. A cooler late winter can slow bud development and nudge bloom later than the recent trend. But the baseline has shifted: warm Marches now occur often enough that early peak blooms are increasingly common.
