Weather Quiz

Prior to February 2019, when was the last time Washington, D.C. had a warmer and wetter than average February ?

A.  1976

B.  1990

C.  1997

D.  2018

February 2019: Month in Review

February 1 Snowfall in Bethesda, Maryland

Despite a relatively benign final few days, this month will be remembered as a warmer and wetter than average one in the Nation’s Capital.  Temperatures will finish approximately 3° above average (looking at daily high and low temperatures) and that makes this DC’s fourth consecutive warmer than average February.  Its average temperature will be just above 42° compared to NOAA's running 30-year (1980-2010) average of 39°.

While finishing 3°/+ above (or below) average is remarkable, this February was not as warm as February 2017 or February 2018 were in the Nation’s Capital.  They were DC’s warmest and third warmest February’s on record.  Conversely, February 2015 was an unusually frigid month in the Nation’s Capital and was DC’s coldest February since 1979.  

It’s unusual for there to be four or more consecutive February’s that are above or below average.  February 2016 through February 2019 was DC’s first streak of at least four consecutive warmer than average February’s since 1997 - 2002.  The last time DC had at least four consecutive colder than average February’s was 1993 – 1996.

While February 2019 was wetter than average in the Nation’s Capital (3.52” of rain vs. 2.62”), there was also below average snowfall this month (3.7” vs. 5.7”).  Nevertheless, since January 2019 was much snowier than average, the 2018-2019 winter season as a whole will finish snowier than average in Washington, D.C.  Incorporating this February, four of the last six February’s have been wetter than average in the Nation’s Capital.

DC’s warmest temperature this month was the record high of 74° on February 5.  Meanwhile, DC’s coldest temperature this month was 18° on February 2.  The warmest day based on average temperature was February 15, with a high/low temperature of 65°/47° that produced an average temperature of 56°.  DC’s coldest day this month occurred February 1, with a high/low temperature of 24°/20°.  It was quite unusual for DC to go from a high temperature of only 24° February 1 (20° below the average high of 44° for the date) to a record high of 74° just four days later. 

It’s worth noting that the record warmth on February 5 with highs in the 70s made for DC’s third consecutive February with at least one day in the 70s.  Dating back to 1993, Washington, D.C. averages roughly one such day every February.  By comparison, DC has averaged roughly the same number of February days with highs in the 20s. 

Is Winter Nearing a Close ?

The three-month period of December, January and February makes up meteorological winter.  The start of “meteorological” spring will arrive on Friday, March 1.  That makes this a good time to see how the 2018-2019 winter season compares to average in the Nation’s Capital.  

This winter will finish with the impressive distinction of being DC’s first where all three months (December – February) have been warmer and wetter than average.  There have been many warmer and wetter than average winters in the Nation’s Capital since weather records began in 1871, but before this winter, it was the result of one or two months that were much warmer or wetter than average.  

December 2018 was 3.8° warmer than average in Washington, D.C.  That’s the seventh time in the last eight years December was warmer than average.  Appropriately, it was also wetter than average with 5.82” of rain capping off DC’s wettest year on record, 2018.  In addition, it was only DC’s third December since 2000 without even a trace of snow.

Although January 2019 had a colder than average second half, the first half was so much warmer than average that the entire month finished 1.2° warmer than average.  It was also a wetter than average month with 3.3” of rain (that includes liquid equivalent of snow) and a snowier than average month with 11.5”.  The bulk of that snow occurred during the January 12 – 14 storm (10.3”).  It was a prolonged snow event with snow observed at National Airport for 35 consecutive hours during the three-day period.  January 2019 was also DC’s snowiest since 2016.  

February 2019 will also finish as a warmer and wetter than average month in the Nation’s Capital.  This month is poised to finish more than 3° above average, making it the fourth consecutive warmer than average February.  According to National Weather Service data, the last time DC had four or more consecutive warmer than average February’s was from 1997 through 2002.  Also, Washington, D.C. has had 3.52” of rain since February 1, compared to the monthly average of 2.62”.  While DC has had below average February snowfall this year (3.7” vs. 5.7”), the 2018-2019 winter season will finish with above average snowfall (16.6” vs. 15.4”). 

A total of 12.64” of rain has occurred since December 1, making the 2018-2019 winter season DC’s wettest since 2002-2003 (13.84”).  That shouldn’t come as a surprise, however, as 11 of the last 13 months have been wetter than average.  Since February 1, 2018, DC has had a total of 72.16” of rain, or more than 30” above the average for the time period.  Despite a few colder and snowier than average days, DC’s 2018-2019 winter season is unique because all three months were both warmer and wetter than average.

An Unprecedented Feat

As the month of February enters its final days, the 2018-2019 winter season is also ending.  December 2018 and January 2019 were warmer than average months.  So far this month, February’s average temperature (combining daily high and low temperatures) is 3.4° above average in Washington, D.C.  This weekend’s rainfall will leave this month well-positioned to become DC’s third consecutive warmer and wetter than average month.

That would make this meteorological winter (comprised of the three-month period of December – February) warmer and wetter than average in the Nation’s Capital.  There have been instances where an entire winter season has finished warmer and wetter than average in DC, but not each of the months individually.  For example, last winter was warmer than average overall, but that was largely due to February 2018 that was DC’s third warmest February on record.  That was more than enough to offset a slightly colder than average (0.3°) January 2018.

The last time all three winter months were warmer than average in the Nation’s Capital was during the 2016-2017 winter season.  However, the last time DC had a wetter than average December, January and February was during the 1993-1994 winter season.  Weather records in Washington, D.C. date back to 1871.  Since then, there have been 17 winters when December, January and February were each warmer than average.  It’s worth pointing out that 10 of those winters occurred since 1990 as urbanization has continued to increase in the DC Metro Area.  By comparison, there were15 winters in the Nation’s Capital when all three months (December, January and February) have each been wetter than average.

The 2018-2019 winter is unique because December, January and February are likely to finish warmer and wetter than average.  Having a warmer or wetter than average winter sometimes hides any bitter cold or appreciable snowfall that may have occurred.  For example, this winter will also finish snowier than average with 16.6” of snow (above the seasonal average of 15.4”).  The period of January 21 – February 1, 2019 also had three days when high temperatures remained at or below 25°.  However, the warmth Washingtonians have experienced this winter has been more than enough to offset those unusually frigid days.

Wetter Than Average Winters (December, January, February) in Washington, D.C.
(Source: National Weather Service, NWS)

1.  1993-1994
2.  1978-1979
3.  1948-1949
4.  1944-1945
5.  1936-1937
6.  1932-1933
7.  1914-1915
8.  1907-1908
9.  1902-1903
10.  1901-1902
11.  1898-1899
12.  1890-1891
13.  1884-1885
14.  1881-1882
15.  1880-1881

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Warmer Than Average Winters (December, January, February) in Washington, D.C.
(Source: NWS)

1.  2016-2017
2.  2011-2012
3.  2007-2008
4.  2004-2005
5.  2001-2002
6.  1998-1999
7.  1997-1998
8.  1996-1997
9.  1991-1992
10.  1990-1991
11.  1974-1975
12.  1973-1974
13.  1951-1952
14.  1948-1949
15.  1931-1932
16.  1889-1980
17.  1879-1880

Winter’s Last Stand ?

3" of snow today in Bethesda, MD

A significant winter storm is impacting the DC Metro Area today.  Ironically, a year ago Washingtonians were enjoying record warmth with highs of 78° and 82° on February 20-21, 2018.  Meanwhile, four years have passed since DC residents experienced the first February record low temperature since 1970 when the temperature plummeted to 5° at National Airport.

I recently wrote about how six of DC’s 10 largest snowstorms have occurred during the month of February.  But none were on or after February 20.  The latest a top 10 snowfall has occurred in Washington, D.C. was during the February 18-19, 1979 storm.  That was DC’s third largest snow event with an official total 18.7” and higher amounts in areas west and north of town.  Washington, D.C. hasn’t even had a February snowfall of at least 5” since February 13, 2014 (5.9”).

Although no top 10 snowfalls have occurred in DC between February 20 and March 31, there have been significant winter storms during that time.  March has actually been the snowiest month of the year in four of the last six years in Washington, D.C.  For example, with 12.7” of snow, March 2014 was DC’s snowiest March since 1960!  March 2014 was also the snowiest on record at Dulles Airport in Sterling, VA (19.8”).  More snow has actually occurred in the Nation’s Capital in March than in February since 2011, with an average of 3.27” in March vs. 3.15” in February.

What late February and March are especially noteworthy for in the Mid-Atlantic Region are large swings in temperature.  It’s not uncommon for temperatures to be in the 60s and 70s one day and for accumulating snow to occur in as little as 48 hours before or after such spring-like warmth.  DC residents had a stellar high temperature of 70° on Saturday, March 15, 2014.  However, within 36 hours, DC residents were experiencing the fifth largest snowstorm to occur in the second half of March.  A combined 7.2” of snow occurred in Washington, D.C. on March 16-17, 2014.  To add to that, DC’s high temperature on March 17, 2014 was only 32° (less than half what it was just two days earlier)!

More recently, a record high temperature of 82° occurred on February 21, 2018, while just two days later the high temperature in the Nation’s Capital was a colder than average 48°.  That should put into perspective that while today’s winter weather has made travel treacherous, the fact is that it won’t stick around long is not unusual this time of year.  While temperatures will languish in the 30s today, high temperatures will reach the 50s tomorrow in the Nation’s Capital.

Presidents Day and Winter Weather

Some Washingtonians may know that some of DC’s largest snowstorms have occurred over the Presidents Day weekend.  While no snow is in store for DC residents this President’s Day, a significant winter storm is on tap this week.  My colleagues and I on the WUSA9 Weather Team are watching the latest developments for Wednesday’s storm.  While it won’t be a top 10 snow event – or even a pure snow event in DC – it will be a high impact storm.  The National Weather Service has issued a “Winter Storm Watch” for much of the DC Metro Area on Wednesday.

Washingtonians average 5.7” of snow in February, or roughly one-third of the annual average of 15.4”.  DC also averages 2.62” of rain in February based on the running 30-year average from 1981 through 2010.  Six of DC’s 10 largest snowstorms overall have occurred in February, ranging from the Valentine’s Day storm of 1899 to 2010’s “Snowmageddon” storm.  Five of DC’s 10 largest snowstorms have also occurred since 1996, or roughly one every four to five years.  

Looking at weather records kept by NOAA, only eight February’s since 1993 have had above average snowfall, while 14 February’s in that time have been warmer than average.  An even higher number, 18, have been drier than average in the Nation’s Capital.  While major winter storms require a specific set of meteorological ingredients to occur (e.g., sufficient cold air, favorable storm track), it’s relatively rare for these ingredients to come together at the right time to produce an epic snow event.

Record February warmth has occurred with an even higher rate of frequency, in the Nation’s Capital, compared to record cold.  Five of DC’s warmest February’s have occurred just since 1990, while all but one of DC’s coldest February’s were prior to 1935.  In the 20-year period from 1999 to 2018, Washington, D.C. had a total of 12 record high temperatures in February, compared to only one record low temperature.  Of course, record cold isn’t needed for snow to occur, but having record warmth much more frequently than record cold is not conducive either.  

Weather records in the Nation’s Capital date back to the 1870s and were kept in a different location prior to National Airport’s opening in the 1940s.  The DC Metro Area was much less developed prior to the 1970s and urbanization has only increased steadily since then.  The increased amount of development has led to a stronger urban heat island effect that’s helped keep the Nation’s Capital generally warmer than it used to be.  Frigid temperatures do still occur but just not with the same frequency as decades ago.