Every day but one this December has been warmer than average in Washington, D.C. and it’s likely the last 8 days of the month will all feature milder than normal temperatures. This December is destined finish as the warmest on record, by a substantial margin, and the warmth climaxes on Christmas Eve and Christmas Day.
Temperatures at times will be more than 30 degrees above normal and numerous records are in jeopardy.
The warmth is a result of a flow of air straight from the deep tropics, circulated by an area of high pressure near Bermuda – more typical of summertime:
— Eric Blake (@EricBlake12) December 23, 2015
Here’s a short guide to records likely to be surpassed if not shattered…
Christmas Eve records
Records for both warmest high and low temperatures will almost certainly fall at the three airports.
Forecast highs Christmas Eve afternoon are in the low-to-mid 70s compared to the current record highs of 69 in D.C. (1933), 65 in Baltimore (1990 and 1982), and 66 at Dulles.
The lows Christmas Eve are forecast to be in the low 60s, while the existing record warmest lows are 58 in D.C. (1891), 53 in Baltimore (1891), and 42 at Dulles (2014 and 1979). Dulles stands to absolutely obliterate the warmest low temperature record by some 20 degrees.
If D.C. does not fall below 60 degrees, it would not only break the daily record for warmest low temperature on Christmas Eve, but also the monthly record (59, Dec. 5, 1973) – which would be impressive so late in the month.
Christmas Day records
Models have somewhat slowed the arrival of modestly cooler air forecast earlier in the week for Christmas Day and are now predicting temperatures comparably warm to Christmas Eve. This means more records could well fall.
The record highs will be a challenge to beat, but are certainly in play given the latest forecast highs in the upper 60s to low 70s. The standing records are 72 in D.C. and Baltimore (1964), and 71 at Dulles (1982 and 1964).
Low temperatures on Christmas will probably only be 55-60 (Christmas night before midnight), some 10 degrees above the previous record warmest lows of 49 in D.C. (1987), 48 in Baltimore (1964), and 50 at Dulles (1982).
There is growing model consensus that Sunday, Dec. 27, will also be remarkably warm with forecast highs of 70 to 75! This means another round of records are possible.
Here are the existing records on that day:
Record highest lows: D.C. 50 (1881); Baltimore 52 (1949); Dulles 52 (1971)
Record highs: D.C. 72 (1971); Baltimore 65 (1949); Dulles 73 (1971)
December monthly records
Currently, this December ranks as the third warmest on record in D.C., Baltimore, and Dulles. But just about a degree separates it from the top and, given the forecast for the next eight days, it is forecast to surge into the number one position at all three airports.
In D.C., the average temperature during the two warmest Decembers on record was 45.6 degrees (1889 and 1984). The projected average temperature by the end of this December, due to the remarkably warm final days, is around 50 or 51 degrees. That is about ten degrees above average – a huge anomaly over an entire month.
(Note: Weather records in D.C. and Baltimore date back to 1872 and 1963 at Dulles. For D.C. and Baltimore, records are now maintained at Reagan National and BWI Airports, but were previously sited in downtown locations prior to the airports).