Warmest December Ever?

Late December Temperature Outlook  (Source: NOAA)

The first half of December has been one for the record books across much of the eastern United States.  Through December 16, this month has had an average temperature (combining daily highs and lows) of 50.3 degrees at National Airport.  That’s almost 9 degrees warmer than the December average in Washington, D.C.  Multiple record highs have been set across the DC Metro Region.

The Nation’s Capital has had seven days with high temperatures of at least 60 degrees so far this month –including a six-day stretch of at least 60 degrees (December 10 – 15).  That’s the warmest such stretch since December 1998.  According to the National Weather Service, the warmest temperature so far this month came on December 13 when it was 71 degrees.  It also hasn’t been “freezing” yet this month.  Although it was 32 degrees once last month, the last time temperatures were below 32 degrees in the Nation’s Capital was March 29 when it was 28 degrees.

Following the second warmest November since 2000 in the Nation’s Capital, December has been so warm that some flowers are in bloom – including some autumn cherry blossoms along the Tidal Basin.  A cold front will pass through the Mid-Atlantic Region today and that will knock temperatures down closer to average tomorrow and Saturday.  Saturday will even be slightly colder than average with highs in the low 40s.  

If that holds true, Saturday would be only the third day this month with temperatures at or below normal levels.  Despite the brief cooldown the next few days, temperatures will promptly return to near average levels on Sunday before becoming warmer than average again next week.  According to NOAA’s National Climatic Data Center, the entire East Coast has an 80% to 90% chance of above average temperatures for the later portion of this month.

The warmest December on record in the Nation’s Capital occurred twice – in 1984 and 1889 – when the monthly average temperature was 45.6 degrees.  There is a good chance this month will surpass that to become the warmest December on record.  It’s important to note, though, that a warmer than average December is not a good indicator of what the rest of the winter will feature.  The last two Decembers have been warmer than average in the Mid-Atlantic Region, but a significant shift in the position of the jet stream helped make January colder than average in both 2013 and 2014.

New Record Highs (Degrees Fahrenheit)

December 12:

Baltimore, MD (BWI Airport): 71 (tied the existing record)

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December 13:

Washington, D.C. (National Airport): 71 (tied the existing record)
Dulles Airport, Sterling, VA: 73
Baltimore, MD (BWI Airport): 72

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December 14:

Dulles Airport, Sterling, VA: 69
Baltimore, MD (BWI Airport): 71 (tied the existing record)