Weather Quiz

 

True or False.  Washington, D.C. has never had a March that was more than 3° warmer than average as well as snowier than average.

 

Spring Weather’s Impact on DC’s Cherry Blossoms

 

The National Park Service announced yesterday that DC’s world famous Yoshino cherry blossoms along the Tidal Basin reached stage three, of six, on the way to reaching peak bloom.  That means the blossoms are in the “extension of florets” stage.  Stage one or when “Green Buds” become visible was reached on March 11, with stage two “Florets visible” having arrived March 16.  The warm weather during the upcoming week will help the blossoms get closer to reaching “peak bloom.”

The cherry blossoms are on track to reach peak bloom on or just ahead of the April average.  The National Park Service still expects peak bloom to occur between April 2 and April 5.  However, they might have to move up those dates given the mild weather on tap this week with highs in the 70s expected in the DC Metro Area on Thursday and Friday.  The Nation’s Capital will flirt with 80° on Friday for the first time this year.  By comparison, DC’s first 80° of 2020 occurred on March 20.

“Peak bloom” occurs when 70% of the blossoms are open and typically last for a few days.  Weather plays a key role in how long peak bloom lasts.  The worst kinds of weather for peak bloom are windy conditions or very warm temperatures. 

The earliest peak bloom was on March 15, 1990.  That was during a five-day stretch DC experienced record warmth with daily highs in the 80s, more characteristic of June.  By comparison, the latest the cherry blossoms have reached peak bloom was on April 18, 1958.  That’s because February and March 1958 were cold and very snowy in the Nation’s Capital. 

More recently, Washingtonians experienced colder and snowier than average February and March’s in both 2014 and 2015.  That contributed to a relatively late peak bloom of April 10 in both years.  When the buds are developing on the cherry trees, temperatures in the 20s for any length of time can damage them.  Such was the case in March 2017 when, according to the National Park Service, “...a late frost that occurred between March 14 and March 16 caused roughly half of the blossoms to be lost.” 

Following DC’s warmest February on record in 2017, the cherry blossoms were well on the way to blooming in early-to-mid March 2017.  That’s why the cold weather in mid-March 2017 was so damaging.  Freezing weather is a significant concern once the buds have developed on the trees.  Fortunately for DC Area residents and tourists alike, the cherry blossoms haven’t had any complications this March on the way to reaching peak bloom.

March Temperature Extremes

 

 

DC’s March temperature is 2.7° warmer than average through March 19.  Average monthly temperature is merely the average of the daily high and low temperatures.  The key reason March’s temperature is so much warmer than average is because of last week’s stretch of four consecutive days that high temperatures were in the 70s.  By comparison, DC didn’t have more than two consecutive 70° March days last year.

Another key difference between last March and this March is the number of times temperatures have fallen below freezing.  DC’s last freeze of the 2019-2020 winter season occurred on March 1, 2020 when the temperature fell to 26° at National Airport.  By comparison, temperatures this month have fallen to 32° or colder on eight occasions, including this morning’s low of 32° at National Airport. 

March 2021 has had several stretches of unique weather.  Five of the first eight days of the month were colder than average, followed by six consecutive warmer than average days – including the record high of 79° on March 11.  Four of the last five days have returned to colder than average. 

It’s easy to understand why DC’s March temperature is considerably warmer than average, despite the near even split of warmer and cooler than average days.  The warmer than average days in the 70s were much warmer than average; more so than the chilly days were cooler than average.  March weather can often be quite streaky as Washingtonians have seen so far this month. 

Precipitation can also be quite variable as the Nation’s Capital recently experienced its driest stretch of weather in roughly 18 months.  The 16 consecutive days without measurable precipitation, from March 2 through March 17, was DC’s longest since there was a 17-day stretch in September 2019.  If no more rain were to occur this month, the 0.66” of rain since March 1 would make this DC’s driest March since 2006 (0.05”).

While snow can occur in late March – and has done so several times over the last decade – none is on the horizon in the Nation’s Capital.  In fact, the DC Metro Area will see a moderating temperature trend during the coming week.  That coincides perfectly with the first day of the National Cherry Blossom Festival today.

Is March Snowfall Common ?

 

Surprisingly, Washingtonians have experienced some of their largest snowfalls in March.  In fact, March has been DC’s snowiest month of the year five times since 2009.  That’s despite the fact it gets harder for snow to accumulate than earlier in the winter due to a higher sun angle and warmer temperatures. 

Given the right conditions, snow can overcome the increasing sun angle that occurs as the month of March wears on.  For example, March 2014 was DC’s snowiest March since 1960 with 12.7” at National Airport and 19.7” at Dulles Airport (snowiest on record).  The largest snow event DC experienced in 2014 occurred exactly seven years ago.  A total of 7.2” fell on March 16-17 and that gave DC residents their snowiest St. Patrick’s Day on record.

More recently, 4.1” of snow occurred in Washington, D.C. on March 21, 2018.  That was DC’s largest snowfall since the January 2016 blizzard.  Some may also recall the historic and deadly “Superstorm of 1993” that brought accumulating snow as far south as Birmingham, Alabama and as far west as Chattanooga, Tennessee.  However, the storm track was such that the snow changed to sleet at the height of the storm, which led to only 6.6” of snow in Washington, D.C. 

With highs ranging from the 70s to the 40s over the last week, March remains a very changeable weather month in the DC Metro Area.  Such was the case in March 1990.  That year the world-famous cherry blossoms along the Tidal Basin reached their earliest peak bloom on record (March 15).  Also, one of the warmest March weeks on record occurred from March 12 – 16, 1990 when there were five consecutive days with high temperatures in the 80s.  That was followed by a high/low temperature of only 42/38 degrees on March 20 at National Airport and 1.9” of snow on March 24. 

In a rare occurrence, March 1990 was both snowier than average and more than 3° warmer than average in the Nation’s Capital.  Also unusual were March 2017 and March 2018, which were cooler than the preceding February’s in Washington, D.C.

Washington, D.C.’s Ten Largest March Snowstorms (Source: NWS)

1.  12.0” – March 27-28, 1891
2.  11.5” – March 28-29, 1942
3.  10.7” – March 7 – 8, 1941
4.  10.0” – March 15 – 16, 1900
5.  9.8” –   March 3 – 4, 1909
6.  8.4” –   March 9, 1999
7.  8.0” –   March 14 – 16, 1937
8.  7.9” –   March 2 – 3, 1960
9.  7.4” –   March 7 – 8, 1911
10. 7.2” –  March 16 – 17, 2014

 

---

Snowiest Marchs, Washington, D.C. (Source: NWS)

1.  19.3” – 1914
2.  17.1” – 1960
3.  17.0” – 1891
4.  15.5” – 1900
5.  12.7   – 2014