Unusual January Cold

Fresh snow on Broomes Island, MD (Courtesy: Kristen Leitch)

Today is the second of three consecutive significantly colder than average days in the Nation’s Capital.  High temperatures tomorrow are only expected to be near the freezing point after highs in the 20s today and yesterday.  In fact, yesterday’s high temperature of 27 degrees at National Airport was the coldest day of the season thus far and the coldest day in Washington, D.C. since February 14, 2016.

Washingtonians have seen 14 streaks of at least three consecutive January days with high temperatures at or below freezing over the last 25 years.  Prior to the current streak, the last to occur was two years ago (January 6 – 8, 2015).   January 2014 had the highest number of days (15) in recent decades with high temperatures at or below freezing.  Meanwhile, January 1994 was the coldest January in Washington, D.C. since 1982, with a monthly average temperature of 28.8 degrees.  

The last January streak of at least four consecutive days with temperatures at or below 32 degrees occurred from January 22 – 25, 2013.  Excluding this month, there has been a total of 91 January days when high temperatures held at or below freezing in Washington, D.C. since 1993.  Only three of those days featured high temperatures in the teens – with one day that saw a high in the single digits (8 degrees on January 19, 1994).  

Subfreezing high temperatures are quite rare in the Nation’s Capital, while highs in the teens are rarer still.  That’s because when arctic air plunges southward, it typically has a chance to moderate somewhat by the time it reaches the Mid-Atlantic Region.  

There have been nine colder than average Januarys in Washington, D.C. dating back to 2000.  However, only seven Januarys have featured above average snowfall in that time.  For example, January 2000’s average temperature was within 0.1 of a degree of average and Washingtonians saw nearly triple the average monthly amount of snowfall (14.5” vs. 5.6”).  That helps show a colder than average month doesn’t always correlate to a snowier than average month.

Some factors, like a fresh snowpack and calm winds, can contribute to making temperatures especially cold given an arctic air mass in January.  Such conditions are ideal for radiational cooling which allows temperatures to fall even lower than they otherwise would if there was no snow cover or if it was windy.  For instance, air temperatures this morning would have been even colder had winds been calm.  Fortunately for those Mid-Atlantic residents who don’t like the cold weather a significant warming trend is on tap for the second half of the work week.