Weather Quiz

September 7, 2017  (Source: WUSA9)

True or False.

With 17 tropical storms, 10 hurricanes, of which, 6 became major hurricanes; 2017 was the busiest Atlantic hurricane season since 2005.

End of Year Weather Extremes

With a high and low temperature of 47°/32° at National Airport yesterday, Washingtonians experienced a colder than average Thanksgiving (55°/39°).  It also made for DC’s coldest Thanksgiving since 2013.  DC residents haven’t had any rainfall on Thanksgiving since 2011 when 0.03” fell.

Variable weather conditions on Thanksgiving Day reflect a larger pattern overall.  The DC Metro Area has a unique geography.  With four distinct seasons, weather conditions can also vary widely from one location to the next over a relatively short distance.  Suburban areas away from the Potomac River or urban heat island of downtown DC often see cooler temperatures.

Such was the case earlier this month on November 11, when the high/low temperatures at National Airport were a frigid 39°/26° and at Dulles Airport where they were 37°/21°.  There can be even larger temperature extremes when there is fresh snow cover.  On December 5, 2002, 6.1” of snow fell at National Airport, while Dulles saw 6.2”.  With the fresh snowfall, clear skies and calm winds, the morning of December 7 was especially frigid with a low temperature of 18° at National Airport and a record low of 1° at Dulles Airport.

Washingtonians got their first taste of record November cold since 1976 earlier this month when the temperature fell to 26° on November 11.  Dulles Airport has had record November cold much more frequently.  It set or tied three record low temperatures between November 18 – 22, 2014.  By comparison, National Airport has had three record high temperatures in the month of November over the last five years (with one each in 2014, 2015 and 2016).

It’s interesting to note that DC’s warmest Thanksgiving occurred on November 22, 2007, with a record high of 77° at National Airport and 75° at Dulles.  Meanwhile, there have been only six Thanksgivings with measurable rainfall in the Nation’s Capital since 1993, but none since 2011.

November 2017 has been a slightly cooler than average with this month’s average temperature (combining daily high/low temperatures) 0.9° below average through November 23 at National Airport.  Over the same period, this month has been 1.6° colder than average at Dulles Airport.  No significant rainfall is expected in the Nation’s Capital over the next week.  Both National and Dulles Airports could finish with less than 2” of rain this month, compared to the November average of 3.17” and 3.41”.

“White Thanksgiving” in the Nation’s Capital?

Thanksgiving weather often varies widely from one year to the next in the Nation’s Capital.  Thanksgiving falls on November 23 this year and the average high/low temperatures in Washington, D.C. are 55°/39°.

DC’s warmest Thanksgiving on record was on November 22, 2007 (77°).  But that’s the average high temperature in Washington, D.C. on September 22.  By comparison, DC’s coldest Thanksgiving Day high temperature came in 1930 when the high temperature was only 30° on November 27.  Weather records in Washington, D.C. date back to 1871.  However, records have been kept at National Airport since it opened in 1941. 

Prior to that, weather measurements were made downtown.  The coldest Thanksgiving on record since National Airport opened occurred on November 23, 1989 and November 28, 1996, when the high temperature was only 35°.  The coldest low temperature at National Airport on Thanksgiving Day was 25° in 2005, while it was 19° on Thanksgiving Day in 1903. 

Areas north and west of downtown DC are often colder, since they are away from the moderating influences of the downtown corridor and the Potomac River.  Snow on Christmas is a rarity in the Nation’s Capital and snow on Thanksgiving is rarer still.  Accumulating snow has only occurred six times on Thanksgiving in Washington, D.C., with the most recent being in 1989.  A total of 1.9” of snow was measured at National Airport on November 23, 1989, following the 1.6” that fell the day before. 

November and December 1989 were so cold in the DC Metro Area that the snow that fell on Thanksgiving Day remained on the ground on Christmas.  More recently, a trace of snow occurred in Washington, D.C. on Thanksgiving in 2010.  By comparison, the last time at least 0.5” of rain occurred in the Nation’s Capital on Thanksgiving was on November 28, 1985 (0.67”).  Sunny, but chilly temperatures are on tap tomorrow for Thanksgiving with highs near 50° in the Nation’s Capital.