Temperature difference from normal over eastern U.S. Christmas Eve morning as analyzed by GFS model. (WeatherBell.com)

Air flowing up the East Coast straight from the deep tropics is obliterating warm weather records at scores of weather stations.

Temperatures are expected to reach at least 70 degrees from Florida to New England, covering more than 1,200 miles. Amazingly, a reporting station in southern Quebec southwest of Montreal hit 70 degrees at 10 a.m. this morning. Bennington, Vt. hit 70 at 11 a.m.

Burlington, Vt. and Norfolk, Va. soared to 68 and 82 degrees, respectively, by early in the afternoon, their warmest temperatures ever recorded during the month of December.

In many places, forecast highs are 30 to 40 degrees warmer than normal – with temperatures more characteristic of May than December.

“It is safe to say Santa could wear Bermuda shorts this year,” wrote Stacie Hanes, a forecaster at the National Weather Service office serving Portland, Maine.

Through 3 p.m., Washington, D.C. had reached at least 71 degrees, passing the record high of 69 from 1933. Amazingly, Baltimore broke its record high for the date at midnight, when the temperature was 66 degrees. Since then, it has warmed to 71 degrees. Dulles has also broken its record high of 66, reaching 71 degrees.

Many of the major weather stations in the eastern third of the U.S. will break records today, if they have not already.


Forecast highs from National Weather Service. Temperatures are circled are forecast to be within one degree of record highs. (WeatherBell.com)

New York City’s Central Park, which was 64 degrees at midnight, broke its record of 63. It has since soared to 71.  Its forecast high in the mid-70s is comparable to its high recorded this past July 4.

Philadelphia has already hit 70 today, breaking its record.  It has reached at least 70 four times this December, the most instances in any winter month on record.

Other cities that have set record highs today, to name just a few, include Charlotte, N.C., Salisbury, Md., Providence, R.I., Boston, Mass., and Buffalo, N.Y.

The record warmth is attributable to a flow of air sourced straight from the tropics.  High pressure over Bermuda is acting like pump, circulating air westward across the tropical Atlantic  then north up the East Coast.

(NWS via @EricHolthaus)
(NWS via @EricHolthaus)

In Washington, D.C., the moisture content of the air, due to its tropical origins, set a new record for all months between December and April Wednesday evening.

[Record tropical moisture in D.C. spurs flash flood risk today]

On Wednesday, as this historically warm and humid air collided with a cold front ejecting out of the Plains, severe weather erupted in the South.  Twenty-nine tornadoes were reported in six states, and there were 10 storm-related fatalities, including six in Mississippi.

[Ferocious, springlike storms kill at least 10 across the South]

The cold front will meet strong resistance from the forceful push of tropical air meaning the Mid-Atlantic, including the D.C. area, will remain unseasonably mild through the holiday weekend.

The record-setting temperatures this Christmas Eve are part and parcel of an exceptionally warm December in the Mid-Atlantic and Northeast.

In Boston, December is running more than ten degrees warmer than normal and 5 degrees above the previous warmest December on record according to the National Weather Service.  Washington, D.C.’s December will close with similar anomalies.

Even while parts of the West have been cold and snowy this month, the warmth in the East has vastly outweighed it. More than 6,500 warm weather records have been set this month in the U.S. compared to less than 300 cold records according to the National Center for Environmental Information.

“None of us, or any of our grandparents, ever experienced a December with weather like this,” wrote Slate.com meteorologist Eric Holthaus.