DC's Weather Roller Coaster !

Frigid Air on the Way to Washington, D.C.  (Source: WUSA9)

This past week has been dominated by large swings in temperature.  The final days of January will be more dramatic with much colder weather.  January 2019 has been 2.7° warmer than average through January 25.  This can largely be attributed to the very warm first nine days of the month when temperatures never fell below freezing.

But then a major shift in the weather pattern occurred, with only seven days that have been milder than average since January 10.  Washingtonians experienced their ninth largest January snow event on record on January 12 – 14 with 10.3” at National Airport.  That was DC’s largest overall snowfall since the January 2016 blizzard.  It was also more snow than during each of the last two winters.

There have been three days this month with high temperatures in the 60s, while two days had temperatures that remained at or below freezing.  On January 20, Washington, D.C. had a high temperature of 56° at 4:30 AM but temperatures dropped precipitously to a daily low of 18° at 11:59 PM after a powerful cold front came through.  DC’s high/low temperatures of 24°/15° on January 21 was its coldest day in more than a year.

While Dulles Airport in nearby Sterling, Virginia, has had below 0° temperatures in three of the last five winters, Washington, D.C., hasn’t been below zero since January 19, 1994 (-4°).  This is largely due to the fact that Dulles Airport is located in a more rural area where there is less of an urban heat island effect.  It’s also away from the moderating influence of the Potomac River. 

Next week much of the eastern United States will experience an arctic outbreak of rare intensity.  A powerful cold front will pass through the Mid-Atlantic Region on Tuesday afternoon, which is expected to produce DC’s coldest temperatures in more than five years.  The last time the Nation’s Capital had a daily high temperature of less than 20° was on January 22, 2014.  If any snow occurs with the passage of the arctic front on Tuesday night, then temperatures could be even colder on Wednesday and Thursday mornings.

Last time High Temperature of Less than 20°

Washington, D.C., National Airport (DCA): 19° (January 22, 2014)
Dulles Airport, Sterling, VA (IAD): 19° (January 6, 2018)
BWI Airport, Baltimore, Maryland: 18° (January 6, 2018)

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Last time High Temperature Less than 10°

DCA: 8° (January 19, 1994)
IAD: 6° (January 19, 1994)
BWI: 5° (January 19, 1994)

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Last time Low Temperature Less than 10°

DCA: 8° (January 7, 2018)
IAD: 9° (January 15, 2019)
BWI: 1° (January 7, 2018)

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Last time Low Temperature Below 0°

DCA: -4° (January 19, 1994)
IAD: -1° (January 7, 2018)
BWI: -1° (February 5, 1996)