Cherry Blossoms in the nation’s capital: How has the weather affected their blooming dates?

March 29, 2013

As the city’s National Cherry Blossom Festival continues (and awaits the actual blooming, forecast around April 5),  I thought I might trace how recent weather changes have affected the blooming dates of the Tidal Basin’s “Somei-Yoshino” cherry trees.

The sun rises yesterday behind the Jefferson Memorial as cherry blossoms hit peak bloom in April 2008 (Kevin Ambrose)
The sun rises behind the Jefferson Memorial as cherry blossoms hit peak bloom in April 2008 (Kevin Ambrose)

As would be expected with the earlier springs of recent years (with the exception of the current one), more frequent early blooming dates are occurring.  The National Park Service (NPS) says the earliest ever recorded in its 92 years of record-keeping was March 15, 1990.  Surprisingly, that March wasn’t exceptionally warm (50.2 degrees, or 3.4 degrees above normal at Reagan National Airport (DCA), although the previous two months were quite mild.

Two other recent contenders for early bloomings were March 17, 2000 (that March averaged 51.7 degrees, 4.9 degrees above normal) and March 20th of last year (monthly average temperature was 56.8 degrees, a full 10 degrees above normal). All of these were within the last 23 years.

Related: D.C.’s cherry blossoms have shifted 5 days earlier: What about global warming and the future?

However, as Jason Samenow pointed out last year, there were three other much earlier years (1921, 1927 and 1945) when peak blooms matched last year’s very early date of March 20.  Of those, March 1921 was quite mild (55.5 degrees, or 8.7 degrees above the current normal) and March 1945 was even milder (56.2 degrees, or 9.4 degrees above normal.) But surprisingly, March 1927, which averaged 47.6 degrees, or less than one degree above normal, also saw a March 20th peak blooming date.  Go figure!

At the other extreme, the cherry blossoms didn’t show their peak splendor in 1958 until April 18, the latest date on record, which is understandable, since March of that year averaged only 41.4 degrees, or 5.4 degrees below normal (with over 10 inches of snow, to boot).  Ironically, two years later, March 1960 turned out to be the coldest month of the 1959-60 winter here (the only time this has happened) and in much of the East (35.6 degrees, or 11.2 degrees below normal, with 17.1 inches of snow—the most March snow in D.C. on record). Yet, the peak bloom date in 1960 was not as late as in 1958.   As a footnote, during the last 10 years, the latest peak bloom date (April 9) occurred in 2005.  The current average is April 4.

Related: Classic cherry blossom photos from the Library of Congress

How do the above dates compare with the blooming dates of the Yoshino cherry trees that might have occurred here say, in the 19th century?  We don’t know for sure, of course, because they weren’t planted yet.  The best way of estimating this comes from a long-time D.C. resident, Reverend Mackee, who lived in Georgetown during the Civil War years. An amateur meteorologist, the Reverend compiled what is believed to be the only complete weather record for the D.C. area during that turbulent period.  Mackee’s records were incorporated in a book, Civil War Weather in Virginia, by Robert K. Krick.

In my Civil War 150 weather post of March 8, 2011, I discussed  Reverend Mackee’s weather observations and the fact that he was also quite attentive with regard to making notes of seasonal changes in flora and fauna and about the first springtime appearance of cherry tree blossoms in D.C. in 1861, ‘62, ‘63, and’65. From 1861 to 1863, he noted, they apparently bloomed no earlier than April 18 and as late as April 30, although during April 1865, the last year of the war, they bloomed around April 6.

These cherry trees were obviously not of the variety donated to Washington by Japan in 1912 and it’s unclear when they would have blossomed in today’s climate. Nevertheless, it is a rough indicator and by comparison with current average blooming dates of cherry trees in the D.C. Tidal Basin, most of the above dates are quite late in the season:  whereas the NPS says the latest peak bloom of the last 10 years was April 9, Rev. Mackee indicated the earliest peak bloom during the Civil War was April 6.

By the way, although we’re now experiencing one of our later peak bloom dates of recent years, the Japanese cherry trees–in Japan, that is—have already bloomed–the earliest they have ever done so, reports CNN and the Dailyi Yomiuri. As in D.C., Japan announced the beginning of their cherry blossom season this past weekend.   So unless I’m missing something, the Japanese seem to time their cherry blossom festivities to coincide with peak blooming, whereas D.C. sets up a fixed date well in advance to accommodate the tourism industry.   Could this be a teachable moment for D.C.?

 Some background on the Washington’s Tidal Basin cherry blossoms

Burning infected Cherry Trees In 1910. (National Park Service)
Burning infected Cherry Trees In 1910. (National Park Service)

On returning from Japan in 1885, Eliza Ruhamah Scidmore attempted to convince the U.S. Army Superintendent of the Office of Public Buildings and Grounds (Col. Spencer Cosby) to plant Japanese cherry trees along Washington’s Potomac waterfront.  Unfortunately, her efforts failed.

But years later, with the help of others, including First Lady Helen Taft, she would eventually succeed and the same U.S. Army Superintendent of the Office of Public Buildings and Grounds who had previously rejected the idea, approved the purchase in 1909.

On January 6, 1910,  however, when Japan’s shipment arrived, there was a major setback, as the trees were infested with insects and nematodes, forcing President Taft to burn the entire stock.  Later, after diplomatic sensitivities were soothed, Japan delivered a second shipment (3,020) of the prized trees, but only 1,800 of the Somei-Yoshino variety that adorn the Tidal Basin.

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A. Camden Walker · March 29, 2013