A springlike weekend with temperatures approaching 70 degrees is ahead, but forecasters are hypothesizing Arctic air could dip southward to push the mercury below normal late in the month.
Temperatures are forecast to reach 60 degrees or higher three days in a row, Saturday through Monday, without a chance for showers until Monday evening.
While that warmth is about 20 degrees above normal, it isn't all that rare.
The last time BWI Marshall Airport did not break 60 degrees at some point in January was 2009. Every other year since at least 2008, at least one January day has surpassed 60 degrees. Last January, on the 7th and the 31st, the airport hit 66 degrees, the same high the National Weather Service is forecasting for Sunday.
Forecasters expect a cold snap is behind the warm spell, though it's still almost a couple of weeks out and therefore could easily change. There were predictions of Arctic air dipping southward in the beginning of December, and the month instead started with five days of 50s, 60s and even 70-degree readings at BWI Marshall Airport.
AccuWeather.com's Henry Margusity expects cold air to spread across the West and Plains over the next week "and over time slosh east." AccuWeather forecasters explained in a release earlier this week:
A phenomenon known as sudden stratospheric warming has occurred in the arctic region during the past few days. The stratosphere is located between 6 miles and 30 miles above the ground.
Often when this occurs, it forces cold air to build in the lowest layer of the atmosphere then to drive southward.
WBAL-TV meteorologist Tony Pann shares forecast models demonstrating the effect on his Facebook page.
Forecasters at the Climate Prediction Center in College Park concur that colder-than-average temperatures are likely to move in from the north, but its forecast maps show it to be less likely to reach Maryland.