The Washington Post
A week from peak blossom bloom
The weather in Washington has turned chilly, but the city’s cherry blossom buds — aided by unseasonably mild weather in February and early March — may be within a week or so of peak bloom.
Because the buds are so far along so soon, we need to bump our peak bloom forecast forward by several days. We now predict peak bloom will occur between March 19 and 23, instead of between March 25 and 29. Our initial forecast was based on computer model projections for more intense and enduring cold weather than we’re actually experiencing.
Nudged ahead by sunshine and highs in the 50s last week, the buds hit Stage 4 out of 6 on Saturday, known as peduncle elongation. During this stage, the stalks bearing the blossom buds extend and, while the buds are still closed, the flowers become visible. Peduncle elongation was reached on the second-earliest date since records of bud stages began in 2004.
On average, peak bloom occurs about a week after peduncle elongation, although it can occur more quickly if the weather is warm or a little slower if it’s cold.
While the weather has turned chillier than normal since late last week and will remain cool through Wednesday, sunny, warmer weather is expected Thursday and Friday, which may be enough to push the buds to their penultimate stage, known as “puffy white.” Once this fifth stage is reached, peak bloom is typically three to five days away.
While some chilly nights are forecast in the week ahead, with low temperatures dipping close to freezing in a few instances, we don’t think they’ll fall enough to harm the buds. Temperatures need to drop below 28 degrees for several hours to cause damage; this happened in 2017 when there was snow and temperatures in the low 20s after the buds hit Stage 4.
A cold front barreling through the Mid-atlantic on Saturday will bring chillier weather Sunday into early next week, but it’s probable the combination of sunshine and highs into the 50s will allow the buds to proceed to peak bloom around that time. Of course, predicting peak bloom is an imperfect science, so it’s not out of the question that even our revised forecast could be off by a day or two on either end.
With the puffy white stage just days away, blooms should gradually become visible, marking the start of a one-to-two-week stretch when you can take in the flowery scenes. Buds on some trees are already starting to blossom.
Peak bloom is defined as when 70 percent of the cherry trees’ buds are flowering. Once flowering occurs, the blossoms can remain on the cherry trees for another week or so if it’s warm and winds are light. But in some years, petals fall off more rapidly because of wind, rain or frost.
Assuming peak bloom occurs between March 19 and 23, it will be about two weeks ahead of the 102-year average of April 4, and 10 days ahead of the recent 30-year average of March 31.
Rising temperatures from human-caused climate change have caused peak bloom to advance by about five days on average since the 1920s. In 16 of the past 20 years, peak bloom has occurred before April 4. Last year, peak bloom occurred on March 21, the eighth-earliest peak on record; this year promises to be similarly early.