The upper air weather pattern is expected to turn abnormally warm again around Christmas. (weatherbell.com)

The Eastern United States is just coming off a December “heat wave” this week, and temperatures will slowly fall back to normal by the weekend. But don’t get too comfortable in your winter coats — another warm-up is expected to peak in the days around Christmas, and it, too, has the potential to topple records.

In the short-term, temperatures across the Eastern United States are forecast to dip to around average over the weekend, and in some places a few degrees below average. The Gulf Coast and Florida will see the “coolest” temperatures of the weekend — 10 to 15 degrees below average for this time in December.

But this cool pattern will not last.


The (brief) cool-down coming this weekend for the Eastern U.S. (weatherbell.com)

Starting Monday, forecast models are predicting the pattern will flip back to what we’ve become so accustomed to this month: a warmer than average East and a cooler than average West.

[The calendar says December but these flowers could not care less]

“Storm systems are forecast to track towards the Great Lakes region,” said Wes Junker, the Capital Weather Gang’s winter weather expert. “Because the flow around storms is counterclockwise, the deep southerly flow to the east of the storms will deliver warm air with southern origins.”

This is the same configuration that delivered record-breaking high temperatures to much of the Eastern United States over the weekend. Temperatures were running 20 to even 30 degrees above average between Friday and Monday. According to the National Climate Data Center, a whopping 1,426 record high temperatures have been broken or tied so far this month, over half of which occurred between Friday and Monday.

[November was warmest such month on record by a huge margin]

The timing of the next warm-up seems to coincide with the days leading up to and around Christmas. The forecast models are in exceptional agreement that temperatures will run 15 to 20 degrees above average — and in some places closer to 30 degrees above average — starting Dec. 23. Temps will continue to run above average in the days after Christmas, just less so. In fact, models are not predicting this warm pattern to really give way until after the month is over.


(NOAA)

Given the agreement among models — and added certainty with a very strong El Nino continuing in the Pacific — NOAA’s Climate Prediction Center is forecasting a 90 percent chance that temperatures will be above average in the second to last week of December, with “above average” chances that the warmth will continue through the first week of January.

[The December full moon falls on Christmas for the firs time in 38 years]

While models were homing in on the Midwest for exceptional warmth in the first half of December, the Mid-Atlantic and Northeast appear to be the targets for the last two weeks of December. Temperatures in the Mid-Atlantic have already been running well above average this month, and the final warm punch could break records for warmest December.


70s on Christmas Eve? It’s possible. (tropicaltidbits.com)

“Temperatures could again flirt with records in some locations unless clouds and or fog help to hold them down,” Junker said. Forecast highs in New York City are in the mid to upper 60s in the days around Christmas. In Raleigh, N.C., highs in the mid-70s are possible.

At Reagan National Airport, D.C.’s official climate monitoring station, the average temperature through Dec. 14 was 50 degrees, more than eight degrees above average. The record warmest December was 45.6 degrees, which was tied between 1889 and 1984. Even with the weekend cool-down, this month will challenge that record thanks to the very warm head-start and the potentially extreme temperature rebound next week.


Temperatures are forecast to run up to 30 degrees above average on Dec. 24 and 25, shown here in degrees Celsius. (weatherbell.com)