Presidents Day and Winter Weather

Some Washingtonians may know that some of DC’s largest snowstorms have occurred over the Presidents Day weekend.  While no snow is in store for DC residents this President’s Day, a significant winter storm is on tap this week.  My colleagues and I on the WUSA9 Weather Team are watching the latest developments for Wednesday’s storm.  While it won’t be a top 10 snow event – or even a pure snow event in DC – it will be a high impact storm.  The National Weather Service has issued a “Winter Storm Watch” for much of the DC Metro Area on Wednesday.

Washingtonians average 5.7” of snow in February, or roughly one-third of the annual average of 15.4”.  DC also averages 2.62” of rain in February based on the running 30-year average from 1981 through 2010.  Six of DC’s 10 largest snowstorms overall have occurred in February, ranging from the Valentine’s Day storm of 1899 to 2010’s “Snowmageddon” storm.  Five of DC’s 10 largest snowstorms have also occurred since 1996, or roughly one every four to five years.  

Looking at weather records kept by NOAA, only eight February’s since 1993 have had above average snowfall, while 14 February’s in that time have been warmer than average.  An even higher number, 18, have been drier than average in the Nation’s Capital.  While major winter storms require a specific set of meteorological ingredients to occur (e.g., sufficient cold air, favorable storm track), it’s relatively rare for these ingredients to come together at the right time to produce an epic snow event.

Record February warmth has occurred with an even higher rate of frequency, in the Nation’s Capital, compared to record cold.  Five of DC’s warmest February’s have occurred just since 1990, while all but one of DC’s coldest February’s were prior to 1935.  In the 20-year period from 1999 to 2018, Washington, D.C. had a total of 12 record high temperatures in February, compared to only one record low temperature.  Of course, record cold isn’t needed for snow to occur, but having record warmth much more frequently than record cold is not conducive either.  

Weather records in the Nation’s Capital date back to the 1870s and were kept in a different location prior to National Airport’s opening in the 1940s.  The DC Metro Area was much less developed prior to the 1970s and urbanization has only increased steadily since then.  The increased amount of development has led to a stronger urban heat island effect that’s helped keep the Nation’s Capital generally warmer than it used to be.  Frigid temperatures do still occur but just not with the same frequency as decades ago.